USE Flag Index

What are USE flags?
For more information on the idea behind USE flags and how to use them, please see our documentation.

Global USE Flags

Flag Description
3dfx Enable support for Voodoo chipsets, also called as 3DFX and TDFX
X Add support for X11
Xaw3d Add support for the 3d athena widget set
a52 Enable support for decoding ATSC A/52 streams used in DVD
aac Enable support for MPEG-4 AAC Audio
aalib Add support for media-libs/aalib (ASCII-Graphics Library)
accessibility Add support for accessibility (eg 'at-spi' library)
acl Add support for Access Control Lists
acpi Add support for Advanced Configuration and Power Interface
adns Add support for asynchronous DNS resolution
afs Add OpenAFS support (distributed file system)
aim Enable AIM IM protocol support
alsa Add support for media-libs/alsa-lib (Advanced Linux Sound Architecture)
altivec Add support for optimizations for G4 and G5/ppc970 processors
ao Use libao audio output library for sound playback
apache2 Add Apache2 support
apm Add APM (Advanced Power Management) support
aqua Include support for the Mac OS X Aqua (Carbon/Cocoa) GUI
atm Enable Asynchronous Transfer Mode protocol support
audiofile Add support for libaudiofile where applicable
avahi Add avahi/Zeroconf support
ayatana Build in support for Ayatana notification using the libindicate or libappindicator plugin
bash-completion Enable bash-completion support
bcmath Add support for libbcmath
berkdb Add support for sys-libs/db (Berkeley DB for MySQL)
bidi Enable bidirectional language support
bindist Flag to enable or disable options for prebuilt (GRP) packages (eg. due to licensing issues)
blas Add support for the virtual/blas numerical library
bluetooth Enable Bluetooth Support
bootstrap !!internal use only!! DO NOT SET THIS FLAG YOURSELF!, used during original system bootstrapping [make stage2]
boundschecking Add the bounds checking patch by Haj Ten Brugge, this will DISABLE the hardened PIE+SSP patches
branding Enable Gentoo specific branding
bsf Enable support for Apache Bean Scripting Framework (dev-java/bsf)
build !!internal use only!! DO NOT SET THIS FLAG YOURSELF!, used for creating build images and the first half of bootstrapping [make stage1]
bzip2 Use the bzlib compression library
cairo Enable support for the cairo graphics library
calendar Add support for calendars (not using mcal!)
canna Add support for the Canna kana to kanji conversion engine
caps Use Linux capabilities library to control privilege
cdb Add support for the CDB database engine from the author of qmail
cdda Add Compact Disk Digital Audio (Standard Audio CD) support
cddb Access cddb servers to retrieve and submit information about compact disks
cdinstall Copy files from the CD rather than asking the user to copy them, mostly used with games
cdparanoia Enable cdparanoia (audio CD ripper) support
cdr Add support for CD writer hardware
cgi Add CGI script support
cjk Add support for Multi-byte character languages (Chinese, Japanese, Korean)
clamav Add support for Clam AntiVirus software (usually with a plugin)
connman Add support for net-misc/connman
coreaudio Build the CoreAudio driver on Mac OS X systems
cracklib Support for cracklib strong password checking
crypt Add support for encryption -- using mcrypt or gpg where applicable
cscope Enable cscope interface -- in vim for example
css Enable reading of encrypted DVDs
ctype Enable ctype functions
cups Add support for CUPS (Common Unix Printing System)
curl Add support for client-side URL transfer library
curlwrappers Add support for using curl in streams
custom-cflags Build with user-specified CFLAGS (unsupported)
cvs Enable CVS (Concurrent Versions System) integration
cxx Build support for C++ (bindings, extra libraries, code generation, ...)
dbi Enable dev-db/libdbi (database-independent abstraction layer) support
dbm Add support for generic DBM databases
dbus Enable dbus support for anything that needs it (gpsd, gnomemeeting, etc)
debug Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces
dedicated Add support for dedicated game servers (some packages do not provide clients and servers at the same time)
dga Add DGA (Direct Graphic Access) support for X
directfb Add support for DirectFB layer (library for FB devices)
djvu Support DjVu, a PDF-like document format esp. suited for scanned documents
doc Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
dri Enable direct rendering: used for accelerated 3D and some 2D, like DMA
dts Enable DTS Coherent Acoustics decoder support
dv Enable support for a codec used by many camcorders
dvb Add support for DVB (Digital Video Broadcasting)
dvd Add support for DVDs
dvdr Add support for DVD writer hardware (e.g. in xcdroast)
eds Enable support for Evolution-Data-Server (EDS)
emacs Add support for GNU Emacs
emboss Add support for the European Molecular Biology Open Software Suite
encode Add support for encoding of audio or video files
enscript Add enscript support to colourize code stored in the repository
evo Add support for mail-client/evolution
examples Install examples, usually source code
exif Add support for reading EXIF headers from JPEG and TIFF images
expat Enable the use of dev-libs/expat for XML parsing
fam Enable FAM (File Alteration Monitor) support
fastcgi Add support for the FastCGI interface
fbcon Add framebuffer support for the console, via the kernel
ffmpeg Enable ffmpeg/libav-based audio/video codec support
fftw Use FFTW library for computing Fourier transforms
filecaps Use Linux file capabilities to control privilege rather than set*id (this is orthogonal to USE=caps which uses capabilities at runtime e.g. libcap)
firebird Add support for the Firebird relational database
flac Add support for FLAC: Free Lossless Audio Codec
flatfile Add dbm support for flat files
fltk Add support for the Fast Light Toolkit gui interface
fontconfig Support for configuring and customizing font access via media-libs/fontconfig
foomaticdb Add support for the foomatic printing driver database
fortran Add support for fortran
freetds Add support for the TDS protocol to connect to MSSQL/Sybase databases
freewnn Add support for FreeWnn kana to kanji conversion engine
frontbase Add support for the frontbase sql server
ftp Add FTP (File Transfer Protocol) support
gcj Enable building with gcj (The GNU Compiler for the Javatm Programming Language)
gd Add support for media-libs/gd (to generate graphics on the fly)
gdbm Add support for sys-libs/gdbm (GNU database libraries)
geoip Add geoip support for country and city lookup based on IPs
ggi Add support for media-libs/libggi (non-X video api/drivers)
gif Add GIF image support
gimp Build a plugin for the GIMP
git Enable git (version control system) support
glut Build an OpenGL plugin using the GLUT library
gmp Add support for dev-libs/gmp (GNU MP library)
gnome Add GNOME support
gnome-keyring Enable support for storing passwords via gnome-keyring
gnuplot Enable support for gnuplot (data and function plotting)
gnutls Add support for net-libs/gnutls (TLS 1.0 and SSL 3.0 support)
gphoto2 Add digital camera support
gpm Add support for sys-libs/gpm (Console-based mouse driver)
gps Add support for Global Positioning System
graphviz Add support for the Graphviz library
gsl Use the GNU scientific library for calculations
gsm Add support for the gsm lossy speech compression codec
gstreamer Add support for media-libs/gstreamer (Streaming media)
gtk Add support for x11-libs/gtk+ (The GIMP Toolkit)
guile Add support for the guile Scheme interpreter
gzip Compress files with Lempel-Ziv coding (LZ77)
handbook Enable handbooks generation for KDE4.
hardened Activate default security enhancements for toolchain (gcc, glibc, binutils)
hddtemp Enable monitoring of hdd temperature (app-admin/hddtemp)
hdf5 Add support for the Hierarchical Data Format v5
hscolour Include coloured haskell sources to generated documentation (dev-haskell/hscolour)
ibm Add support for IBM ppc64 specific systems
iconv Enable support for the iconv character set conversion library
icq Enable ICQ IM protocol support
icu Enable ICU (Internationalization Components for Unicode) support, using dev-libs/icu
idn Enable support for Internationalized Domain Names
ieee1394 Enable FireWire/iLink IEEE1394 support (dv, camera, ...)
imagemagick Enable support for Imagemagick (image converter)
imap Add support for IMAP (Internet Mail Application Protocol)
imlib Add support for imlib, an image loading and rendering library
infiniband Enable Infiniband RDMA transport support
inifile Add dbm support for .ini files
inotify Enable inotify filesystem monitoring support
introspection Add support for GObject based introspection
iodbc Add support for iODBC library
ios Enable support for Apple's iDevice with iOS operating system (iPad, iPhone, iPod, etc)
ipod Enable support for iPod device access
ipv6 Add support for IP version 6
iwmmxt Add support for optimizations for ARM iwMMXt instructions
jabber Enable jabber IM protocol support
jack Add support for the JACK Audio Connection Kit
java Add support for Java
javascript Enable javascript support
jbig Enable jbig-kit support for tiff, Hylafax, ImageMagick, etc
jingle Enable voice calls for jabber
jit Enable just-in-time compilation for improved performance. May prevent use of some PaX memory protection features in Gentoo Hardened.
joystick Add support for joysticks in all packages
jpeg Add JPEG image support
jpeg2k Support for JPEG 2000, a wavelet-based image compression format
kde Add support for KDE (K Desktop Environment)
kerberos Add kerberos support
kolab Add support for the Kolab groupware server
kontact Enable support for the KDE personal information manager (kde-base/kdepim*)
ladspa Enable the ability to support ladspa plugins
lame Prefer using LAME libraries for MP3 encoding support
lapack Add support for the virtual/lapack numerical library
lash Add LASH Audio Session Handler support
latex Add support for LaTeX (typesetting package)
lcms Add lcms support (color management engine)
ldap Add LDAP support (Lightweight Directory Access Protocol)
libass SRT/SSA/ASS (SubRip / SubStation Alpha) subtitle support
libav Prefer libav over ffmpeg whenever both are supported
libcaca Add support for colored ASCII-art graphics
libedit Use the libedit library (replacement for readline)
libffi Enable support for Foreign Function Interface library
libnotify Enable desktop notification support
libsamplerate Build with support for converting sample rates using libsamplerate
libwww Add libwww support (General purpose WEB API)
lirc Add support for lirc (Linux's Infra-Red Remote Control)
livecd !!internal use only!! DO NOT SET THIS FLAG YOURSELF!, used during livecd building
lm_sensors Add linux lm_sensors (hardware sensors) support
lua Enable Lua scripting support
lzma Support for LZMA (de)compression algorithm
lzo Enable support for lzo compression
m17n-lib Enable m17n-lib support
mad Add support for mad (high-quality mp3 decoder library and cli frontend)
maildir Add support for maildir (~/.maildir) style mail spools
matroska Add support for the matroska container format (extensions .mkv, .mka and .mks)
matrox Add Matrox MGA support to mplayer
mbox Add support for mbox (/var/spool/mail) style mail spools
memlimit Add memory usage limiting in supporting programs
mhash Add support for the mhash library
migemo Enable migemo support for Japanese
mikmod Add libmikmod support to allow playing of SoundTracker-style music files
milter Add sendmail mail filter (milter) support
mime Add MIME support
minimal Install a very minimal build (disables, for example, plugins, fonts, most drivers, non-critical features)
mmap Add mmap (memory map) support
mms Support for Microsoft Media Server (MMS) streams
mng Add support for libmng (MNG images)
modplug Add libmodplug support for playing SoundTracker-style music files
modules Build the kernel modules
mono Build Mono bindings to support dotnet type stuff
motif Add support for the Motif toolkit
mozilla Add support for the Mozilla web-browser
mp3 Add support for reading mp3 files
mp4 Support for MP4 container format
mpeg Add libmpeg3 support to various packages
mpi Add MPI (Message Passing Interface) layer to the apps that support it
mplayer Enable mplayer support for playback or encoding
msn Enable MSN Messenger IM protocol support
mssql Add support for Microsoft SQL Server database
mtp Enable support for Media Transfer Protocol
mule Add multi-language support to XEmacs
multilib On 64bit systems, if you want to be able to compile 32bit and 64bit binaries
musepack Enable support for the musepack audio codec
musicbrainz Lookup audio metadata using MusicBrainz community service (musicbrainz.org)
mysql Add mySQL Database support
mysqli Add support for the improved mySQL libraries
nas Add support for network audio sound
ncurses Add ncurses support (console display library)
neXt Enable neXt toolkit
neon Enable optimization support for ARM NEON processors
netboot Enable network booting
netcdf Enable NetCDF data format support
networkmanager Enable net-misc/networkmanager support
nis Support for NIS/YP services
nls Add Native Language Support (using gettext - GNU locale utilities)
nntp Add support for newsgroups (Network News Transfer Protocol)
nocd Install all files required to run the application without a CD mounted
nptl Enable support for Native POSIX Threads Library, the new threading module (requires linux-2.6 or better usually)
nsplugin Build plugin for browsers supporting the Netscape plugin architecture (that is almost any modern browser)
ocaml Add support/bindings for the Ocaml language
ocamlopt Enable ocamlopt support (ocaml native code compiler) -- Produces faster programs (Warning: you have to disable/enable it at a global scale)
oci8 Add Oracle 8 Database Support
oci8-instant-client Use dev-db/oracle-instantclient-basic as Oracle provider instead of requiring a full Oracle server install
odbc Add ODBC Support (Open DataBase Connectivity)
offensive Enable potentially offensive items in packages
ofx Enable support for importing (and exporting) OFX (Open Financial eXchange) data files
ogg Add support for the Ogg container format (commonly used by Vorbis, Theora and flac)
openal Add support for the Open Audio Library
openexr Support for the OpenEXR graphics file format
opengl Add support for OpenGL (3D graphics)
openmp Build support for the OpenMP (support parallel computing), requires >=sys-devel/gcc-4.2 built with USE="openmp"
oracle Enable Oracle Database support
orc Use dev-lang/orc for just-in-time optimization of array operations
osc Enable support for Open Sound Control
oscar Enable Oscar (AIM/ICQ) IM protocol support
oss Add support for OSS (Open Sound System)
pam Add support for PAM (Pluggable Authentication Modules) - DANGEROUS to arbitrarily flip
pch Enable precompiled header support for faster compilation at the expense of disk space and memory (>=sys-devel/gcc-3.4 only)
pcmcia Add support for PCMCIA slots/devices found on laptop computers
pcntl Add support for process creation functions
pcre Add support for Perl Compatible Regular Expressions
pda Add support for portable devices
pdf Add general support for PDF (Portable Document Format), this replaces the pdflib and cpdflib flags
perl Add optional support/bindings for the Perl language
php Include support for the PHP language
pie Build programs as Position Independent Executables (a security hardening technique)
plasma Build optional KDE plasma addons
plotutils Add support for plotutils (library for 2-D vector graphics)
png Add support for libpng (PNG images)
policykit Enable PolicyKit authentication support
portaudio Add support for the crossplatform portaudio audio API
posix Add support for POSIX-compatible functions
postgres Add support for the postgresql database
postscript Enable support for the PostScript language (often with ghostscript-gpl or libspectre)
ppds Add support for automatically generated ppd (printing driver) files
prefix Defines if a Gentoo Prefix offset installation is used
prelude Add support/bindings for the Prelude Intrusion Detection System
profile Add support for software performance analysis (will likely vary from ebuild to ebuild)
pulseaudio Add support for PulseAudio sound server
python Add optional support/bindings for the Python language
qdbm Add support for the qdbm (Quick Database Manager) library
qmail-spp Add support for qmail SMTP plugins
qt4 Add support for the Qt GUI/Application Toolkit version 4.x
qt5 Add support for the Qt 5 application and UI framework
quicktime Add support for OpenQuickTime
radius Add support for RADIUS authentication
raw Add support for raw image formats
rdesktop Add support for the remote desktop protocol, usually used to connect to Windows servers
readline Enable support for libreadline, a GNU line-editing library that almost everyone wants
recode Enable support for the GNU recode library
rss Enable support for RSS feeds
ruby Add support/bindings for the Ruby language
samba Add support for SAMBA (Windows File and Printer sharing)
sasl Add support for the Simple Authentication and Security Layer
savedconfig Use this to restore your config from /etc/portage/savedconfig ${CATEGORY}/${PN}. Make sure your USE flags allow for appropriate dependencies
scanner Add support for scanner hardware (e.g. build the sane frontend in kdegraphics)
sdl Add support for Simple Direct Layer (media library)
seamonkey Add support for the Seamonkey web-browser
seccomp Enable seccomp for system call filtering
selinux !!internal use only!! Security Enhanced Linux support, this must be set by the selinux profile or breakage will occur
semantic-desktop Cross-KDE support for semantic search and information retrieval
session Add persistent session support
sharedmem Add support for shared memory use
shorten Add support for the shorten audio compressor
simplexml Support for SimpleXML
skey Enable S/Key (Single use password) authentication support
slang Add support for the slang text display library (it's like ncurses, but different)
slp Add Service Locator Protocol support
smartcard Enable smartcard support
smp Enable support for multiprocessors or multicore systems
sndfile Add support for libsndfile
snmp Add support for the Simple Network Management Protocol if available
soap Add support for SOAP (Simple Object Access Protocol)
sockets Add support for tcp/ip sockets
socks5 Add support for the socks5 proxy
sound Enable sound support
source Zip the sources and install them
sox Add support for Sound eXchange (SoX)
speex Add support for the speex audio codec (used for speech)
spell Add dictionary support
sqlite Add support for sqlite - embedded sql database
ssl Add support for Secure Socket Layer connections
startup-notification Enable application startup event feedback mechanism
static !!do not set this during bootstrap!! Causes binaries to be statically linked instead of dynamically
static-libs Build static versions of dynamic libraries as well
subversion Enable subversion (version control system) support
suid Enable setuid root program, with potential security risks
svg Add support for SVG (Scalable Vector Graphics)
svga Add support for SVGAlib (graphics library)
sybase Add support for the Sybase SQL Database Server
sybase-ct Add support for Sybase-CT
symlink Force kernel ebuilds to automatically update the /usr/src/linux symlink
syslog Enable support for syslog
systemd Enable use of systemd-specific libraries and features like socket activation or session tracking
sysvipc Support for System V-compatible inter-process communication
szip Use the szip compression library
taglib Enable tagging support with taglib
tcl Add support the Tcl language
tcmalloc Use the dev-util/google-perftools libraries to replace the malloc() implementation with a possibly faster one
tcpd Add support for TCP wrappers
test Workaround to pull in packages needed to run with FEATURES=test. Portage-2.1.2 handles this internally, so don't set it in make.conf/package.use anymore
theora Add support for the Theora Video Compression Codec
threads Add threads support for various packages. Usually pthreads
tidy Add support for HTML Tidy
tiff Add support for the TIFF image format
timidity Build with Timidity++ (MIDI sequencer) support
tk Add support for Tk GUI toolkit
tokenizer Add support for the PHP file parser
truetype Add support for FreeType and/or FreeType2 fonts
uclibc Enable uclibc specific patches and build or link uclibc
udev Enable virtual/udev integration (device discovery, power and storage device support, etc)
udisks Enable storage management support (automounting, volume monitoring, etc)
unicode Add support for Unicode
upnp Enable UPnP port mapping support
upnp-av Enable UPnP audio/video streaming support
upower Enable power management support
usb Add USB support to applications that have optional USB support (e.g. cups)
v4l Enable support for video4linux (using linux-headers or userspace libv4l libraries)
vaapi Enable Video Acceleration API for hardware decoding
vala Enable bindings for dev-lang/vala
vanilla Do not add extra patches which change default behaviour; DO NOT USE THIS ON A GLOBAL SCALE as the severity of the meaning changes drastically
vcd Video CD support
vdpau Enable the Video Decode and Presentation API for Unix acceleration interface
vhosts Add support for installing web-based applications into a virtual-hosting environment
videos Install optional video files (used in some games)
vim-syntax Pulls in related vim syntax scripts
vnc Enable VNC (remote desktop viewer) support
vorbis Add support for the OggVorbis audio codec
wayland Enable dev-libs/wayland backend
wavpack Add support for wavpack audio compression tools
wddx Add support for Web Distributed Data eXchange
webkit Add support for the WebKit HTML rendering/layout engine
wifi Enable wireless network functions
wmf Add support for the Windows Metafile vector image format
wxwidgets Add support for wxWidgets/wxGTK GUI toolkit
x264 Enable h264 encoding using x264
xattr Add support for extended attributes (filesystem-stored metadata)
xcb Support the X C-language Binding, a replacement for Xlib
xcomposite Enable support for the Xorg composite extension
xemacs Add support for XEmacs
xface Add xface support used to allow a small image of xface format to be included in an email via the header 'X-Face'
xft Build with support for XFT font renderer (x11-libs/libXft)
xine Add support for the XINE movie libraries
xinerama Add support for the xinerama X11 extension, which is mandatory if you work in multiple monitors setup
xinetd Add support for the xinetd super-server
xml Add support for XML files
xmlrpc Support for xml-rpc library
xmp Enable support for Extensible Metadata Platform (Adobe XMP)
xmpp Enable support for Extensible Messaging and Presence Protocol (XMPP) formerly known as Jabber
xosd Sends display using the X On Screen Display library
xpm Add support for XPM graphics format
xscreensaver Add support for XScreenSaver extension
xv Add in optional support for the Xvideo extension (an X API for video playback)
xvid Add support for xvid.org's open-source mpeg-4 codec
yahoo Enable Yahoo Messenger IM protocol support
yaz Add in optional support for the Z39.50 Protocol for Information Retrieval (YAZ)
zeroconf Support for DNS Service Discovery (DNS-SD)
zlib Add support for zlib (de)compression
zsh-completion Enable zsh completion support

Local USE Flags

app-accessibility

brltty

api build brltty's application program interface
beeper support the console tone generator
contracted-braille support in-line contracted braille
fm support for the sound card synthesizer
midi support the musical instrument digital interface
pcm support for sound card digital audio
speech speech support

eflite

16k_voice Use a higher-quality voice.

emacspeak

espeak Adds support for the espeak tts engine

festival-it

mbrola Adds support for mbrola voices

freetts

jsapi build Java Speech API (JSAPI)
mbrola Adds support for mbrola voices

orca

braille Enable braille support

simon

kdepim Use kde-base/kdepimlibs
opencv Use media-libs/opencv
sphinx Build sphinx backend (pulls app-accessibility/julius if disabled

speech-dispatcher

espeak Adds support for espeak speech engine
flite Adds support for flite speech engine

speechd-el

brltty brltty support

app-admin

bcfg2

cheetah Include dev-python/cheetah support
genshi Include dev-python/genshi support
server Installs scripts to be used on the server-side of this app

clsync

cgroups Use cgroups to limit /dev access.
cluster Enable clustering support (allows master-master clsync on multiple hosts). Not fully implemented yet.
control-socket Enable AF_UNIX control socket support.
extra-debug Enable extra debugging. This will hurt performance badly. Be ready for tons of output.
extra-hardened Enable extra security checks. This will hurt performance.
gio Enable GIO for FS monitoring (glib based alternative to inotify interface, not recommended; if both are compiled, may be selected at runtime).
highload-locks Allows to use spinlocks for short delays instead of mutexes, but only on SMP systems.
namespaces Enable namespaces isolation.
seccomp Enable seccomp for system call filtering.

collectd

collectd_plugins_aggregation Build the aggregation plugin (aggregate multiplte values into a single value)
collectd_plugins_apache Build the apache input plugin (transferred bytes, handled requests, detailed scoreboard statistics)
collectd_plugins_apcups Build the apcups input plugin (UPS charge, load, input/output/battery voltage, etc.)
collectd_plugins_ascent Build the ascent input plugin (statistics about a free server for World of Warcraft)
collectd_plugins_battery Build the battery input plugin (charge, current and voltage of ACPI and PMU based laptop batteries)
collectd_plugins_bind Build the bind input plugin (name server and resolver statistics)
collectd_plugins_cgroups Build the cgroups CPU accounting collection plugin
collectd_plugins_conntrack Build the conntrack input plugin (number of nf_conntrack entries)
collectd_plugins_contextswitch Build the contextswitch input plugin (number of context switches done by the operating system)
collectd_plugins_cpu Build the cpu input plugin (time spent in the system, user, nice, idle, and related states)
collectd_plugins_cpufreq Build the cpufreq input plugin (CPU frequency, for laptops with speedstep or similar)
collectd_plugins_csv Build the csv output plugin (write to comma separated values (CSV) files)
collectd_plugins_curl Build the curl input plugin (parse statistics from websites using regular expressions)
collectd_plugins_curl_json Build the curl_json input plugin (get json data via curl and parse it)
collectd_plugins_curl_xml Build the curl_xml input plugin (get xml data via curl and parse it)
collectd_plugins_dbi Build the dbi input plugin (execute SQL statements on databases and interpret the reply)
collectd_plugins_df Build the df input plugin (mountpoint usage)
collectd_plugins_disk Build the disk input plugin (sectors read/written, number of read/write actions, average completion time of IO-operations)
collectd_plugins_dns Build the dns input plugin (collects statistics of your DNS traffic on port udp/53)
collectd_plugins_email Build the email input plugin (opens a UNIX domain socket and starts accepting connections on that socket)
collectd_plugins_entropy Build the entropy input plugin (available entropy on a system)
collectd_plugins_ethstat Build the ethstat input plugin (performance statistics of Linux ethernet cards)
collectd_plugins_exec Build the exec input/output plugin (executes scripts / applications and reads values back)
collectd_plugins_filecount Build the filecount input plugin (countd the number of files in a directory and all its subdirectories)
collectd_plugins_fscache Build the fscache input plugin (information about the caching infrastructure for network file-systems etc)
collectd_plugins_gmond Build the gmond input plugin (receive data from gmond, the client daemon of the Ganglia project)
collectd_plugins_hddtemp Build the hddtemp input plugin (temperature of hard disks)
collectd_plugins_interface Build the interface input plugin (information about traffic, packets and errors of interfaces)
collectd_plugins_ipmi Build the ipmi input plugin (read hardware sensors from servers using the Intelligent Platform Management Interface (IPMI))
collectd_plugins_iptables Build the iptables input plugin (statistics from a ip_tables based packet filter)
collectd_plugins_irq Build the irq input plugin (number of times each interrupt has been handled by the os)
collectd_plugins_java Build the java input plugin (embeds a JVM into collectd for writing plugins)
collectd_plugins_libvirt Build the libvirt input plugin (statistics about virtualized guests on a system)
collectd_plugins_load Build the load input plugin (system load)
collectd_plugins_logfile Build the logfile output plugin (writes log messages to a text file)
collectd_plugins_lvm Build the LVM input plugin
collectd_plugins_madwifi Build the madwifi input plugin (information about Atheros wireless LAN chipsets)
collectd_plugins_match_empty_counter Build the match_empty_counter filter plugin
collectd_plugins_match_hashed Build the match_hashed filter plugin
collectd_plugins_match_regex Build the match_regex filter plugin
collectd_plugins_match_timediff Build the match_timediff filter plugin
collectd_plugins_match_value Build the match_value filter plugin
collectd_plugins_mbmon Build the mbmon input plugin (information from mainboard sensors)
collectd_plugins_md Build the md input plugin (disk states in Linux md devices)
collectd_plugins_memcachec Build the memcachec input plugin (connects to a memcached server)
collectd_plugins_memcached Build the memcached input plugin (connects to a memcached daemon)
collectd_plugins_memory Build the memory input plugin (physical memory utilization)
collectd_plugins_multimeter Build the multimeter input plugin (reads a voltage or current from a multimeter connected to a serial bus)
collectd_plugins_mysql Build the mysql input plugin (connects to an MySQL-database and issues a SHOW STATUS command)
collectd_plugins_netlink Build the netlink input plugin (opens a netlink socket to the Linux kernel for getting statistics)
collectd_plugins_network Build the network input/output plugin (communicates with other instances of collectd)
collectd_plugins_nfs Build the nfs input plugin (usage of the Network File System)
collectd_plugins_nginx Build the nginx input plugin (number of requests handled by the nginx daemon)
collectd_plugins_notify_desktop Build the notify_desktop output plugin (uses libnotify to display notifications to the user)
collectd_plugins_notify_email Build the notify_email output plugin (uses libESMTP to send notifications to a configured email address)
collectd_plugins_ntpd Build the ntpd input plugin (queries an NTP server)
collectd_plugins_numa Build the numa input plugin (statistics of the Linux Non-Uniform Memory Access (NUMA) subsystem)
collectd_plugins_nut Build the nut input plugin (collects UPS statistics using the Network UPS Tools)
collectd_plugins_olsrd Build the olsrd input plugin (reads information about the Optimized Link State Routing daemon)
collectd_plugins_onewire Build the onewire input plugin (collects temperature information from sensors)
collectd_plugins_openvpn Build the openvpn input plugin (reads the status file printed by OpenVPN)
collectd_plugins_oracle Build the oracle input plugin (SQL-queries one or more Oracle database systems)
collectd_plugins_perl Build the perl language binding plugin (embeds a Perl interpreter into collectd for writing plugins)
collectd_plugins_ping Build the ping input plugin (measures network latency)
collectd_plugins_postgresql Build the postgresql input plugin (connects to and executes SQL statements on a PostgreSQL database)
collectd_plugins_powerdns Build the powerdns input plugin (connects to a local PowerDNS instance)
collectd_plugins_processes Build the processes input plugin (statistics about processes)
collectd_plugins_protocols Build the protocols input plugin (network protocols)
collectd_plugins_python Build the python language binding plugin (embeds a Python interpreter into collectd for writing plugins)
collectd_plugins_routeros Build the routeros input plugin (collect information on devices running RouterOS)
collectd_plugins_rrdcached Build the rrdcached input/output plugin (connects to rrdcached and submits updates for RRD files)
collectd_plugins_rrdtool Build the rrdtool output plugin (writes values to RRD-files)
collectd_plugins_sensors Build the sensors input plugin (uses lm-sensors to read hardware sensors)
collectd_plugins_serial Build the serial input plugin (collects the traffic on serial interfaces)
collectd_plugins_snmp Build the snmp input plugin (read values from network devices using SNMP)
collectd_plugins_statsd Build the statsd input plugin (accepts statsd-type metrics from a UDP socket)
collectd_plugins_swap Build the swap input plugin (amount of memory currently written to swap)
collectd_plugins_syslog Build the syslog output plugin (receives messages from collectd and dispatches them to syslog)
collectd_plugins_table Build the table input plugin (parses table-like structured plain text)
collectd_plugins_tail Build the tail input plugin (follows logfiles as e.g. tail -f)
collectd_plugins_target_notification Build the target_notification filter plugin
collectd_plugins_target_replace Build the target_replace filter plugin
collectd_plugins_target_scale Build the target_scale filter plugin
collectd_plugins_target_set Build the target_set filter plugin
collectd_plugins_tcpconns Build the tcpconns input plugin (number of TCP connections to or from a specified port)
collectd_plugins_teamspeak2 Build the teamspeak2 input plugin (collects traffic statistics from a teamspeak2 instance)
collectd_plugins_ted Build the ted input plugin (connects to The Energy Detective and reads the current power over connected power lines)
collectd_plugins_thermal Build the thermal input plugin (ACPI thermal zone information)
collectd_plugins_threshold Build the threshold plugin (checks values against configured thresholds and creates notifications if values are out of bounds)
collectd_plugins_tokyotyrant Build the tokyotyrant input plugin (number of records and file size from a running Tokyo Tyrant server)
collectd_plugins_unixsock Build the unixsock output plugin (opens a UNIX domain socket and accepts connections)
collectd_plugins_uptime Build the uptime input plugin (system uptime)
collectd_plugins_users Build the users input plugin (number of users currently logged in)
collectd_plugins_uuid Build the uuid plugin (tries hard to determine the UUID of the system it is running on)
collectd_plugins_varnish Build the varnish input plugin
collectd_plugins_vmem Build the vmem input plugin (information about the virtual memory subsystem)
collectd_plugins_vserver Build the vserver input plugin (virtual servers running on a system)
collectd_plugins_wireless Build the wireless input plugin (signal quality, signal power and signal-to-noise ratio for wireless LAN cards)
collectd_plugins_write_graphite Build the write_graphite output plugin (sends the values collected by collectd to Carbon, the storage layer of the Graphite time-series database)
collectd_plugins_write_http Build the write_http output plugin (sends the values collected by collectd to a web-server)
collectd_plugins_write_mongodb Build the write_mongodb output plugin (sends the values collected by collectd to a MongoDB)
contrib Install user-contributed files in the doc directory

conky

apcupsd enable support for sys-power/apcupsd
audacious enable monitoring of music played by media-sound/audacious
eve enable support for the eve-online skill monitor
iostats enable support for per-task I/O statistics
lua enable if you want Lua scripting support
lua-cairo enable if you want Lua Cairo bindings for Conky (also enables lua support)
lua-imlib enable if you want Lua Imlib2 bindings for Conky (also enables lua and imlib support)
math enable support for glibc's libm math library
moc enable monitoring of music played by media-sound/moc
mpd enable monitoring of music controlled by media-sound/mpd
nano-syntax enable syntax highlighting for app-editors/nano
nvidia enable reading of nvidia card temperature sensors via media-video/nvidia-settings
portmon enable support for tcp (ip4) port monitoring
thinkpad enable support for IBM/Lenovo notebooks
weather-metar enable support for metar weather service
weather-xoap enable support for metar and xoap weather service
xmms2 enable monitoring of music played by media-sound/xmms2

consul

web Build the web UI.

diamond

mongo Enable MongoDB support
redis Enable Redis support

diradm

automount Support for automount data in LDAP
irixpasswd Support for storing separate IRIX passwords

elektra

gcov Enable coverage support
ini Enable ini support
keytometa Enable keytometa support
simpleini Enable simpleini support
uname Enable uname information for the key database
yajl Enable yajl support

gkrellm

X Build both the X11 gui (gkrellm) and the server (gkrellmd). Disabling this flag builds the server only.
gnutls Enable SSL support for mail checking with net-libs/gnutls (overrides 'ssl' USE flag)
hddtemp Enable monitoring harddrive temperatures via app-admin/hddtemp
lm_sensors Enable monitoring sensors via sys-apps/lm_sensors
ntlm Enable NTLM authentication for mail checking with net-libs/libntlm
ssl Enable SSL support for mail checking with dev-libs/openssl

glance

swift Adds swift storage support

hddtemp

network-cron Monthly cronjob to update hddtemp.db.

keepass

aot Generate native code at build time, rather than runtime.

lastpass

chrome Support for www-client/chrome
chromium Support for www-client/chromium
firefox Support for www-client/firefox

lastpass-cli

X Use x11-misc/xclip or x11-misc/xsel to copy passwords to the clipboard.
pinentry Use app-crypt/pinentry to prompt for passwords.

logrotate

acl Installs acl support
cron Installs cron file
selinux Installs Security Enhanced Linux support

mate-system-tools

caja Adds support for the Caja file manager
nfs Adds support for NFS shares

matter

entropy Add Entropy support

mcollective

client Install client utilities

mms-agent

monitoring Install the monitoring agent

openrc-settingsd

systemd Use the versions of dbus and polkit files provided by sys-apps/systemd

packagekit-base

command-not-found Enable packagekit support on shell "command not found"
cron Install cron script for auto-update
entropy Enable Entropy backend
introspection Use dev-libs/gobject-introspection Enable introspection
pm-utils Add pm-utils (suspend/resume) functionalities

pass

X Use x11-misc/xclip to copy passwords to the clipboard.
dmenu Add support for x11-misc/dmenu with the 'passmenu' program.
fish-completion Enable fish completion support.
git Use dev-vcs/git for password revisions.
importers Allow importing passwords from other password managers using various contributed scripts.

puppet

augeas Enable augeas support
diff Enable diff support
rrdtool Enable rrdtool support
shadow Enable shadow support

puppet-agent

puppetdb Adds puppetdb support

puppetserver

puppetdb Adds support for connecting to puppetdb

pwgen

livecd Install init script for root password scrambling on boot

rsyslog

dbi Build the general database output module (requires dev-db/libdbi)
elasticsearch Build the Elasticsearch output module (requires net-misc/curl)
gcrypt Add support for encrypted log files using dev-libs/libgcrypt
jemalloc Use dev-libs/jemalloc for allocations.
kerberos Build the GSSAPI input and output module (requires virtual/krb5)
mongodb Build the MongoDB output module (requires dev-libs/libmongo-client)
mysql Build the MySQL databse output module (requires virtual/mysql)
normalize Build the normalize modify module (requires dev-libs/libee and dev-libs/liblognorm)
omudpspoof Build the udpspoof output module (requires net-libs/libnet)
postgres Build the PostgreSQL database output module (requires dev-db/postgresql-base)
rabbitmq Build the RabbitMQ output module (requires net-libs/rabbitmq-c)
redis Build the Redis output module using (requires dev-libs/hiredis)
relp Build the Reliable Event Logging Protocol (RELP) output module (requires dev-libs/librelp)
rfc3195 Build the rfc3195 input module (requires dev-libs/liblogging)
rfc5424hmac Build the rfc5424hmac modify module (requires dev-libs/openssl)
snmp Build the snmp modify and output module (requires net-analyzer/net-snmp)
ssl Add support for encrypted client/server communication (requires net-libs/gnutls)
systemd Build the journal input and output module (requires sys-apps/systemd)
usertools Installs the user tools (rsgtutil, rscryutil...) corresponding to the set USE flags
zeromq Build the ZeroMQ input and output modules (requires net-libs/zeromq)

sagan

libdnet Add support for dev-libs/libdnet
lognorm Add support for log/rules normalizations via dev-libs/liblognorm
pcap Add support for network packet capture via net-libs/libpcap
smtp Build witch SMTP (E-Mail) support
snort Add support to interact with Snort IDE using net-analyzer/snortsam'

sagan-rules

lognorm Install normalize rules support with dev-libs/liblognorm

salt

api Enable support for salt-api.
cherrypy Enable support for using cherrypy.
gnupg Enable support for gnupg via python-gnupg.
keyring Enable support for keyrings via python-keyring.
libcloud Enable salt-cloud support via libcloud.
libvirt Support managing virtual machines with app-emulation/libvirt.
mako Add support for using the mako template engine for parsing salt states.
mongodb Support returning data to a mongodb server.
neutron Support the OpenStack neutron network service.
nova Enable support for the OpenStack Nova API
openssl Add support for using TLS via OpenSSL.
raet Add support for the new RAET transport.
redis Support returning data to a redis database.
timelib Use timelib to parse english textual date descriptions.
zeromq Add support for the zeromq transport.

sshguard

ipfilter Enable ipfilter firewall support (only for *bsd)

sudo

offensive Let sudo print insults when the user types the wrong password.
sendmail Allow sudo to send emails with sendmail.

sysklogd

logrotate use app-admin/logrotate for rotating logs rather than custom cron scripts

syslog-ng

amqp Enable support for AMQP destinations
json Enable support for JSON template formatting via dev-libs/json-c
mongodb Enable support for mongodb destinations
pacct Enable support for reading Process Accounting files (EXPERIMENTAL, Linux only)
redis Enable support for Redis destinations
smtp Enable support for SMTP destinations
spoof-source Enable support for spoofed source addresses

sysstat

cron Install /etc/cron.d script to periodically run sar
isag Install isag, the Interactive System Activity Graph tool

testdisk

ewf Include ewf library
ntfs Include the ability to read NTFS filesystems
reiserfs Include reiserfs reading ability

tripwire

ssl Adds support for Secure Socket Layer connections
static Builds the package statically
tools Installs app-admin/mktwpol, providing scripts for the installation/setup of tripwire, including generating the tripwire policy file and maintenance of the tripwire database

ulogd

json Build JSON output plugin to save packets in JSON file format.
mysql Build MySQL output plugin to save packets in a mysql database.
nfacct Build NFACCT input plugin to support traffic accounting via nfnetlink_acct.
nfct Build NFCT input plugin to support stateful flow-based logging via nf_conntrack_netlink.
nflog Build NFLOG input plugin to support stateless packet-based logging via nfnetlink_queue.
pcap Build PCAP output plugin to save packets in libpcap file format.
postgres Build PGSQL output plugin to save packets in a postgres database.
sqlite Build SQLITE3 output plugin to save packets in a sqlite database.
ulog Build ULOG input plugin to support deprecated packet-based logging via ULOG target.

webalizer

xtended Include the 404 extension

webapp-config

portage Propagete python_targets dependencies to sys-apps/portage

yaala

storable Support for persistence of Perl data structures.

app-antivirus

clamav

clamdtop A Top like tool which shows what clamd is currently scanning amongst other things
metadata-analysis-api Enables collection of file property metadata using ClamAV API for analysis by ClamAV bytecode programs.

app-arch

cabextract

extras Install experimental extra tools: wince_info and wince_rename for examining and processing Windows CE installation cabinet header files; cabinfo for examining the structure of a cab file.

cfv

bittorrent Enable support for checking .torrent files

dpkg

update-alternatives Install update-alternatives

dump

ermt encrypted rmt support

engrampa

caja Enable engrampa to integrate with mate-base/caja by providing entries in its context menu

file-roller

nautilus Enable file-roller to integrate with gnome-base/nautilus by providing entries in its context menu
packagekit Enable support for the distro-neutral package manager GUI app-admin/packagekit

gzip

pic disable optimized assembly code that is not PIC friendly

innoextract

c++0x Compile innoextract using the C++11 standard.

libarchive

bzip2 Allow accessing bzip2-compressed archives through libbz2 (which comes with app-arch/bzip2). This only affects libarchive's native support: bsdtar will keep using bunzip2 as a filter if that's not built-in.
e2fsprogs Use file flags from sys-fs/e2fsprogs headers instead of virtual/os-headers headers
nettle Use dev-libs/nettle as crypto backend
zlib Allow accessing gzip-compressed archives through sys-libs/zlib. This only affects libarchive's native support: bsdtar will keep using gunzip as a filter if that's not built-in. It's also needed for supporting extraction of ZIP files.

libzpaq

jit Enable just-in-time compilation for faster compression (requires SSE2)

lz4

valgrind Enable usage of dev-util/valgrind in tests

p7zip

rar Enable support for non-free rar decoder

pbzip2

symlink Install symlinks which override app-arch/bzip2 implementation

rar

all_sfx Install all SFX (Self-Extracting) files rather than just the native format (allows creation of Windows EXEs on Linux ELF systems)

tar

minimal just install `tar`

unzip

natspec Use dev-libs/libnatspec to correctly decode non-ascii file names archived in Windows.

zip

natspec Use dev-libs/libnatspec to correctly decode non-ascii file names archived in Windows.

app-backup

amanda

s3 Support for backing up to the Amazon S3 system
xfs Support for backing up raw XFS filesystems using xfsdump

backup-manager

s3 Support for backing up to the Amazon S3 system

bacula

bacula-clientonly Disable DB support, and just build a client
bacula-nodir Disable building of director
bacula-nosd Disable building of storage daemon
logwatch Install support files for logwatch

bareos

cephfs Enable cephfs storage backend
clientonly Only install file-daemon (client)
director Install director
fastlz Enable support vor lz4, lz4hc and lzfast using dev-libs/bareos-fastlzlib
glusterfs Enable glusterfs storage backend
lmdb enable build of LMDB support for faster accurate backup
logwatch Install support files for logwatch
ndmp Enable support for NDMP (Network Data Management Protocol)
rados Enable rados storage backend
scsi-crypto Enable low level SCSI crypto support
sql-pooling Enable SQL pooling support
storage-daemon Install storage daemon (bareos-sd)

boxbackup

client-only Disable server support, and just build a client

dar

dar32 Enables --enable-mode=32 option, which replace infinite by 32 bit integers
dar64 Enables --enable-mode=64 option, which replace infinite by 64 bit integers
gcrypt Enables strong encryption support

deja-dup

nautilus Build gnome-base/nautilus extension

duplicity

s3 Support for backing up to the Amazon S3 system

holland-backup-mysql-meta

lvm Install Holland LVM Plugin
mysqldump Install Holland mysqldump Plugin
mysqlhotcopy Install Holland mysqlhotcopy Plugin

rear

udev Have ReaR start backup when attaching your USB drive.

snapper

btrfs Include Btrfs support sys-fs/btrfs-progs
ext4 Include Ext4 support sys-fs/e2fsprogs
lvm Enable LVM thinprovisioned snapshots support sys-fs/lvm2
xattr Add support for getting and setting POSIX extended attributes, through sys-apps/attr.

tsm

hsm Installs Tivoli Storage Manager for Space Management
tsm_cit IBM Tivoli Common Inventory Technology
tsm_hw Difference snapshot support for NetApp and N-Series file servers

app-benchmarks

jmeter

beanshell Enable BeanShell scripting support

ltp

expect Build against the expect library for interactive testing
open-posix Build and install the POSIX testsuite
pm Build and install the power management testsuite
rt Build and install the realtime testsuite

ramspeed

pic Force shared libraries to be built as PIC (this is slower)

sysbench

aio Enable libaio support

app-cdr

backlite

mplayer Add support for mplayer preview in addition to X11 and phonon

brasero

libburn Enable dev-libs/libburn backend
nautilus Build the gnome-base/nautilus extension
packagekit Enable support for the distro-neutral package manager GUI app-admin/packagekit
playlist Enable support for playlists through dev-libs/totem-pl-parser
tracker Enable audio playlist search using the app-misc/tracker indexer

cdemu

cdemu-daemon Pull app-cdr/cdemu-daemon dependency, useful in chroot environment (bug #315491). Do not disable until you know what you are doing.

cdrdao

gcdmaster Enable building of gcdmaster application

cdrkit

hfs Provide building of HFS (Apple) CD-images

cuetools

extras Install additional script that tag files based on cue/toc file information

disc-cover

cdrom Enable audio CD support. This is not needed to make www-apps/disc-cover work.

gaffitter

scripts Install additional gaffitter scripts for external programs

k3b

emovix Enable burning support for eMoviX images

mirage2iso

pinentry Support app-crypt/pinentry password input backend.

mybashburn

normalize Add support for normalizing audio file volume levels

app-crypt

aespipe

asm Enable assebly modules
cpu_flags_x86_padlock Use VIA padlock instructions, detected at run time, code still works on non-padlock processors

ccid

twinserial Enable twinserial reader

codecrypt

cryptopp Build algorithms that need Crypto++ support dev-libs/crypto++

eid-mw

gtk Enable the dialog pages, by using x11-libs/gtk+:2
xpi Build and install an extension for Mozilla browsers.

ekeyd

minimal Only install the ekey-egd-linux service rather than the full ekeyd package.
munin Install a plugin for net-analyzer/munin to graph statistical data from ekeyd.
usb Build the libusb-based userland daemon for accessing the EntropyKey (alternative to the CDC USB driver). It is suggested to use this option by default, as the CDC driver in the kernel often seems to be fragile (or the gadget implementation on the EntropyKey is too buggy), and can cause various problems.

gnupg

mta Build mta support using virtual/mta.
smartcard Build scdaemon software. Enables usage of OpenPGP cards. For other type of smartcards, try app-crypt/gnupg-pkcs11-scd.
tools Install extra tools.
usb Build direct CCID access for scdaemon; requires dev-libs/libusb.

gpgme

common-lisp Install common-lisp files

hashcat-gui

cuda Install oclhashcat-{plus,lite}-bin to take advantage of hardware cuda support.
opencl Install oclhashcat-{plus,lite}-bin to take advantage of hardware opencl support.

heimdal

hdb-ldap Adds support for LDAP as a database backend
otp Adds support for one-time passwords
pkinit Adds support for PKINIT for the initial ticket

hmaccalc

fips Enable NSS FIPS mode and support only the FIPS-compliant functions

johntheripper

cuda Use nvidia cuda toolkit for speeding up cracking on capable devices
mozilla Support mozilla password cracking
opencl Enable opencl support for speeding up cracking on capable devices

kstart

afs Enables afs support which means you can acquire an afs token and set PAGs. It's recommended to set this USE if you need authenticated access to an AFS cell for your daemon/app.

libsecret

vala Enable bindings for dev-lang/vala

libu2f-host

systemd Use user ACLs rather than plugdev group to give user access to the HIDRAW device.

mit-krb5

doc Creates and installs the API and implementation documentation. This is only useful if you want to develop software which depends on kerberos.
keyutils Enable for the keyring ccache using keyutils.
openldap Enable support for ldap as a database backend.
pkinit Enable pkinit support for the initial ticket.

oclhashcat-lite-bin

virtualcl Support for Mosix VirtualCL Clustering Platform

oclhashcat-plus-bin

virtualcl Support for Mosix VirtualCL Clustering Platform

ophcrack

tables Require the additional tables used to carry out cracking (app-crypt/ophcrack-tables)

ophcrack-tables

vistafree Installs the free Vista ophcrack tables
xpfast Installs the fast XP ophcrack tables
xpsmall Installs the small free XP ophcrack tables

p11-kit

asn1 Enable ASN.1 certificate support
trust Build the trust policy module

pinentry

clipboard Enable clipboard integration

qca

botan Enable botan plugin
gcrypt Enable gcrypt plugin
gpg Enable GnuPG plugin
logger Enable logger plugin
nss Enable NSS plugin
openssl Enable OpenSSL plugin
pkcs11 Enable PKCS#11 plugin
sasl Enable SASL plugin
softstore Enable softstore plugin

seahorse

ldap Enable seahorse to manipulate GPG keys on a LDAP server.

shishi

3des Enable 3DES encryption/checksum type.
aes Enable AES encryption/checksum types.
arcfour Enable ARCFOUR encryption/checksum type.
des Enable DES related encryption/checksum types.
md Enable unkeyed MD4/MD5 checksum types.
null Enable dummy NULL encryption/checksum type.

tc-play

openssl Use openssl crypto backend.

tpm-tools

pkcs11 Build Token data management utilities based on OpenCryptoki's (dev-libs/opencryptoki) PKCS#11 implementation.

truecrypt

asm Enable assembly for optimization

app-dicts

aspell-be

classic Support classic spelling by default

gwaei

hunspell Enable app-text/hunspell spellchecking and morphological analysis
mecab Enable app-text/mecab support
unique Enable single instance support using dev-libs/libunique.

myspell-pt

preao Use the pre ortographic agreement version of the dictionary

app-doc

clsync-docs

api Install doxygen generated API docs.

csound-manual

html Install HTML documentation

doxygen

clang support for sys-devel/clang assisted parsing
dot allow to create dot graphs using media-gfx/graphviz
doxysearch build doxyindexer and doxysearch.cgi

linuxfromscratch

htmlsingle Install all-on-one-page HTML version.

pms

binary Download pre-built files instead of building from sources
html Generate PMS as .html as well

root-docs

api Generate html API documentation
http Build HttpServer documentation
math Provide all math related documentation
metric Default to A4 paper size and metric measurement. Letter will be used otherwise

tldp-howto

html Install multi-chapter HTML docs
htmlsingle Install all-on-one-page HTML docs
pdf Install pdf docs
text Install plain-text docs

app-editors

bluefish

gucharmap Enable gucharmap dictionary plugin

emacs

athena Enable the MIT Athena widget set (x11-libs/libXaw)
games Support shared score files for games
gconf Use gnome-base/gconf to read the system font name
gfile Use gfile (dev-libs/glib) for file notification
gsettings Use gsettings (dev-libs/glib) to read the system font name
gtk3 Link against version 3 of the GIMP Toolkit instead of version 2 (x11-libs/gtk+)
gzip-el Compress bundled Emacs Lisp source
hesiod Enable support for net-dns/hesiod
imagemagick Use media-gfx/imagemagick for image processing
libxml2 Use dev-libs/libxml2 to parse XML instead of the internal Lisp implementations
pax_kernel Enable building under a PaX enabled kernel
source Install C source files and make them available for find-function
toolkit-scroll-bars Use the selected toolkit's scrollbars in preference to Emacs' own scrollbars
wide-int Prefer wide Emacs integers (typically 62-bit). This option has an effect only on architectures where "long" and "long long" types have different size.

emacs-vcs

athena Enable the MIT Athena widget set (x11-libs/libXaw)
games Support shared score files for games
gconf Use gnome-base/gconf to read the system font name
gfile Use gfile (dev-libs/glib) for file notification
gsettings Use gsettings (dev-libs/glib) to read the system font name
gtk3 Link against version 3 of the GIMP Toolkit instead of version 2 (x11-libs/gtk+)
gzip-el Compress bundled Emacs Lisp source
hesiod Enable support for net-dns/hesiod
imagemagick Use media-gfx/imagemagick for image processing
libxml2 Use dev-libs/libxml2 to parse XML instead of the internal Lisp implementations
pax_kernel Enable building under a PaX enabled kernel
source Install C source files and make them available for find-function
toolkit-scroll-bars Use the selected toolkit's scrollbars in preference to Emacs' own scrollbars
wide-int Prefer wide Emacs integers (typically 62-bit). This option has an effect only on architectures where "long" and "long long" types have different size.

fe

sendmail Send mail after editor abend

gedit-plugins

charmap Insert special characters just by clicking on them
git Shows document changes related to git's HEAD
terminal Embed a terminal in the bottom pane
zeitgeist Build the plugin to inject events to gnome-extra/zeitgeist

gvim

luajit Use dev-lang/luajit instead of dev-lang/lua
netbeans Include netbeans external editor integration support
racket Enable support for Scheme using dev-lang/racket

jasspa-microemacs

nanoemacs Build NanoEmacs instead of MicroEmacs

joe

xterm Enable full xterm clipboard support

latexila

latexmk Install dev-tex/latexmk (used by default for the build tools)
rubber Install dev-tex/rubber (can be used for the build tools)

leafpad

emacs Enable Emacs key theme

mousepad

gtk3 Use GTK+3 instead of GTK+2

nano

debug Enable debug messages and assert warnings. Note that these will all be sent straight to stderr rather than some logging facility.
justify Enable justify/unjustify functions for text formatting.
magic Add magic file support (sys-apps/file) to automatically detect appropriate syntax highlighting
minimal Disable all fancy features, including ones that otherwise have a dedicated USE flag (such as spelling).

ne

tinfo Link against libtinfo from sys-libs/ncurses

tea

aspell Enable spellchecking using app-text/aspell
hunspell Enable spellchecking using app-text/hunspell

vim

X Link console vim against X11 libraries to enable title and clipboard features in xterm
luajit Use dev-lang/luajit instead of dev-lang/lua
racket Enable support for Scheme using dev-lang/racket
vim-pager Install vimpager and vimmanpager links

vim-qt

luajit Use dev-lang/luajit instead of dev-lang/lua
racket Enable support for Scheme using dev-lang/racket

xemacs

athena Chooses the MIT Athena widget set
dnd Enables support for the x11-libs/dnd drag-n-drop library
eolconv Support detection and translation of newline conventions
pop Support POP for mail retrieval
xim Enable X11 XiM input method

xmlcopyeditor

guidexml Install GuideXML templates to work with Gentoo official docs

zile

valgrind Enable usage of dev-util/valgrind in tests

app-emacs

anything

extensions Install optional extensions

auctex

preview-latex Use bundled preview-latex

bbdb

tex Install plain TeX support files
vm Add support for app-emacs/vm

calfw

howm Add support for the app-emacs/howm note-taking tool

company-mode

ropemacs Install backend for dev-python/ropemacs

emacs-common-gentoo

games Support shared score files for games

emhacks

jde Enable support for Java Development Environment

magit

contrib Install user-contributed files

org-mode

contrib Install user-contributed files
odt-schema Install non-free schema files for OpenDocument Text exporter

remember

bbdb Include support for app-emacs/bbdb
planner Include support for app-emacs/planner

slime

xref Install xref.lisp cross-referencing tool

vm

bbdb Include support for app-emacs/bbdb

wanderlust

bbdb Include support for app-emacs/bbdb

wikipedia-mode

outline-magic Enable support for outline-mode extensions (app-emacs/outline-magic)

app-emulation

aranym

fullmmu Enable full 68040 MMU emulation
lilo Enable Linux-m68k loader
usbhost Enable NatFeat USB

bochs

3dnow Enable support for emulating 3DNow! instructions (incomplete)
avx Enable support for emulating Advanced Vector Extensions (AVX)
debugger Enable debugger (slows down emulation)
gdb Enable support for the remote GDB stub
x86-64 Enable support for emulation of 64-bit CPUs

crossover-bin

capi Enable ISDN support via CAPI

docker

apparmor Enable AppArmor support.
aufs Enables dependencies for the "aufs" graph driver, including necessary kernel flags.
btrfs Enables dependencies for the "btrfs" graph driver, including necessary kernel flags.
contrib Install additional contrib scripts and components.
device-mapper Enables dependencies for the "devicemapper" graph driver, including necessary kernel flags.
experimental Enable features labelled by upstream to be of "experimental" quality and not yet ready for general consumption.
lxc Enables dependencies for the "lxc" execution driver.
overlay Enables dependencies for the "overlay" graph driver, including necessary kernel flags.

dosemu

fluidsynth use media-sound/fluidsynth for MIDI emulation

e-uae

capslib Add CAPS library support
sdl-sound Use media-libs/sdl-sound for audio output

free42

alsa Adds support for Advanced Linux Sound Architecture

fuse-utils

gcrypt Use dev-libs/libgcrypt for low-level crypto of some features, including logfiles.

ganeti

drbd Enable DRBD support
filestorage Enable File Storage
haskell-daemons Build haskell daemons instead of python
htools Enable htools support
kvm Enable KVM support
lxc Enable Linux Countainers support
monitoring Enable the ganeti monitoring daemon
multiple-users Enable support for running VMs as different users.
rbd Enable rados block device support via sys-cluster/ceph
xen Enable Xen support

libguestfs

erlang Build Erlang bindings
fuse Enable image mount support via fuse
inspect-icons Use media-gfx/icoutilsfor acces icon file in image and inspect it
introspection Use dev-libs/gobject-introspection for introspection
systemtap Use dev-util/systemtap to inspect VM via "probes" way

libspectrum

gcrypt Use dev-libs/libgcrypt for low-level crypto of some features, including logfiles.

libvirt

apparmor Enable AppArmor support
audit support sys-process/audit
firewalld DBus interface to iptables/ebtables allowing for better runtime management of your firewall.
fuse Allow LXC to use sys-fs/fuse for mount points
glusterfs Enable GlusterFS support via sys-cluster/glusterfs
iscsi Allow using an iSCSI remote storage server as pool for disk image storage
libvirtd Builds the libvirtd daemon as well as the client utilities instead of just the client utilities
lvm Allow using the Logical Volume Manager (sys-apps/lvm2) as pool for disk image storage
lxc Support management of Linux Containers virtualisation (app-emulation/lxc)
macvtap Support for MAC-based TAP (macvlan/macvtap). For networking instead of the normal TUN/TAP. It has its advantages and disadvantages. macvtap support requires very new kernels and is currently evolving. Support for this is experimental at best.
nfs Allow using Network File System mounts as pool for disk image storage
numa Use NUMA for memory segmenting via sys-process/numactl and sys-process/numad
openvz Support management of OpenVZ virtualisation (see sys-kernel/openvz-sources)
parted Allow using real disk partitions as pool for disk image storage, using sys-block/parted to create, resize and delete them.
pcap Support auto learning IP addreses for routing
phyp Support IBM HMC / IVM hypervisor via PHYP protocol
qemu Support management of QEMU virtualisation (app-emulation/qemu)
rbd Enable rados block device support via sys-cluster/ceph
uml Support management of User Mode Linux virtualisation
vepa Virtual Ethernet Port Aggregator (VEPA) / 802.1Qbg support. Relies on macvtap support.
virt-network Enable virtual networking (NAT) support for guests. Includes all the dependencies for NATed network mode. Effectively any network setup that relies on libvirt to setup and configure network interfaces on your host. This can include bridged and routed networks ONLY if you are allowing libvirt to create and manage the underlying devices for you. In some cases this requires enabling the 'netcf' USE flag (currently unavailable).
virtualbox Support management of VirtualBox virtualisation (one of app-emulation/virtualbox or app-emulation/virtualbox-ose)
wireshark-plugins Build the net-analyzer/wireshark plugin for the Libvirt RPC protocol
xen Support management of Xen virtualisation (app-emulation/xen)

lxc

cgmanager Enable support for cgroup management using app-admin/cgmanager

lxd

image Installs the lxd-images image-fetching script

open-vm-tools

doc Generate API documentation
fuse Build vmblock-fuse in favor of FUSE based blocking mechanism for DnD
grabbitmqproxy Enable grabbitmqproxy
pic Force shared libraries to be built as PIC
vgauth Enable vgauth

open-vm-tools-kmod

vmhgfs Build the vmhgfs module for file sharing support with the host
vmxnet Build the vmxnet module (older virtual NIC)

playonlinux

winbind Enables support for the winbind auth daemon

q4wine

gnome Use the gksu sudo GUI for managing the devices
icoutils Enable icoutils support
kde Use the kdesu sudo GUI for managing the devices
wineappdb Enable Win AppDB browser subsystem

qemu

accessibility Adds support for braille displays using brltty
aio Enables support for Linux's Async IO
alsa Enable alsa output for sound emulation
curl Support ISOs / -cdrom directives vis HTTP or HTTPS.
fdt Enables firmware device tree support
glusterfs Enables GlusterFS cluster fileystem via sys-cluster/glusterfs
gtk2 Use gtk-2 instead of gtk-3
iscsi Enable direct iSCSI support via net-libs/libiscsi instead of indirectly via the Linux block layer that sys-block/open-iscsi does.
jpeg Enable jpeg image support for the VNC console server
ncurses Enable the ncurses-based console
nfs Enable NFS support
numa Enable NUMA support
pin-upstream-blobs Pin the versions of BIOS firmware to the version included in the upstream release. This is needed to sanely support migration/suspend/resume/snapshotting/etc... of instances. When the blobs are different, random corruption/bugs/crashes/etc... may be observed.
png Enable png image support for the VNC console server
pulseaudio Enable pulseaudio output for sound emulation
rbd Enable rados block device backend support, see http://ceph.newdream.net/wiki/QEMU-RBD
sdl Enable the SDL-based console
sdl2 Use libsdl2 instead of libsdl
snappy Enable support for snappy compression
spice Enable Spice protocol support via app-emulation/spice
ssh Enable SSH based block device support via net-libs/libssh2
static Enables both 'static-softmmu' and 'static-user'
static-softmmu Builds the Software MMU (system) targets as static binaries
static-user Build the User targets as static binaries
systemtap Enable SystemTAP/DTrace tracing
tci Enable the TCG Interpreter which can speed up or slowdown workloads depending on the host and guest CPUs being emulated. In the future it will be a runtime option but for now its compile time.
tls Enable TLS support for the VNC console server. For 1.4 and newer this also enables WebSocket support. For 2.0 through 2.3 also enables disk quorum support.
usb Enable USB passthrough via dev-libs/libusb
usbredir Use sys-apps/usbredir to redirect USB devices to another machine over TCP
uuid Enable UUID support in the vdi block driver
vde Enable VDE-based networking
vhost-net Enable accelerated networking using vhost-net, see http://www.linux-kvm.org/page/VhostNet
virtfs Enable VirtFS via virtio-9p-pci / fsdev. See http://wiki.qemu.org/Documentation/9psetup
vte Enable terminal support (x11-libs/vte) in the GTK+ interface
xattr Add support for getting and setting POSIX extended attributes, through sys-apps/attr. Requisite for the virtfs backend.
xen Enables support for Xen backends
xfs Support xfsctl() notification and syncing for XFS backed virtual disks.

spice

client Build the spicec client app (does not reduce dependencies at the moment).
smartcard Enable smartcard remoting using app-emulation/libcacard

spice-vdagent

consolekit Use sys-auth/consolekit to determine the master vdagentd in case of multiple running vdagentds (highly recommended)

uae

scsi Enable the uaescsi.device

vice

ethernet Enable ethernet emulation
fullscreen Enable the ability to run fullscreen
gtk2 Use GTK+2 for GUI instead of GTK+3
memmap Enable extra monitor features
sdlsound Use media-libs/libsdl for sound support
vte Enable support for x11-libs/vte in the GTK+ interface
xrandr Enable support for the X xrandr extension

virt-manager

policykit Enables sys-auth/polkit authentication support, required when using app-emulation/libvirt with PolicyKit authentication
sasl Depend on the proper libraries needed to connect to SASL-enabled libvirtd instances (e.g. Kerberos-protected instances).

virt-viewer

spice Support connecting to SPICE-enabled virtual machines.
vnc Support connecting to VNC-enabled virtual machines.

virt-what

dmi Use sys-apps/dmidecode to read firmware data

virtualbox

additions Install Guest System Tools ISO
extensions Install extension module packages
headless Build without any graphic frontend
sdk Enable building of SDK
udev Controls installation of special USB udev rules.
vboxwebsrv Build and install the VirtualBox webservice

virtualbox-bin

additions Install Guest System Tools ISO
chm Install kchmviewer binary to enable online help (in MS CHM format)
headless Install without any graphic frontend
rdesktop-vrdp Install the rdesktop client integration
sdk Enable building of SDK
vboxwebsrv Install the VirtualBox webservice

virtualbox-modules

pax_kernel Apply patch needed for pax enabled kernels

vmware-modules

pax_kernel Apply patch needed for pax enabled kernels
vmci Build the Virtual Machine Communication Interface module; disable this if you want to use the module from the mainline kernel
vsock Build the VMware VMCI transport for Virtual Sockets; disable this if you want to use the module from the mainline kernel

vmware-player

vmware-tools Install VMware Tools images

vmware-workstation

ovftool Install OVF tool.
server Install VMware Workstation Server component.
vix Install VIX. The VIX API allows you to write programs and scripts that automate virtual machine operations, and run programs or manipulate files within guest operating systems.
vmware-tools Install VMware Tools images

vov

gprof build with profiling support

wine

capi Enable ISDN support via CAPI
custom-cflags Bypass strip-flags; use at your own peril
dos Pull in games-emulation/dosbox to run DOS applications
gecko Add support for the Gecko engine when using iexplore
mono Add support for .NET using Wine's Mono add-on
netapi Use libnetapi from net-fs/samba to support Windows networks in netapi32.dll
opencl Enable OpenCL support
osmesa Add support for OpenGL in bitmaps using libOSMesa
pcap Support packet capture software (e.g. wireshark)
perl Install helpers written in perl (winedump/winemaker)
pipelight Apply unofficial Wine-Staging patches for Pipelight/Silverlight support
prelink Run prelink on DLLs during build -- do not disable if you do not know what this means as it can break things at runtime
realtime Pull in sys-auth/rtkit for low-latency pulseaudio support
run-exes Use Wine to open and run .EXE and .MSI files
s3tc Pull in media-libs/libtxc_dxtn for DXTn texture compression, needed for many games
samba Add support for NTLM auth. see http://wiki.winehq.org/NtlmAuthSetupGuide and http://wiki.winehq.org/NtlmSigningAndSealing
staging Apply unofficial Wine-Staging patches for advanced feature support that haven't made it into upstream Wine yet

winetricks

rar Pull in app-arch/unrar for extraction of rar-compressed game files

x48

readline Enables support for libreadline

xe-guest-utilities

xenstore Use xenstore binaries bundled by Citrix instead of building app-emulation/xen-tools

xen

efi Adds efi boot support, requires LDFLAG -melf_x86_64 for amd64
flask Enable the Flask XSM module from NSA
pae Enable support for PAE kernels (usually x86-32 with >4GB memory)
xsm Enable the Xen Security Modules (XSM)

xen-tools

api Build the C libxenapi bindings
flask Enable the Flask XSM module from NSA
hvm Enable support for hardware based virtualization (VT-x,AMD-v)
ocaml Enable support for the ocaml language
ovmf Enable support to boot UEFI guest vm, needed by hvm
pam Enable pam support
pygrub Install the pygrub boot loader
qemu Enable IOEMU support via the use of qemu-dm
screen Enable support for running domain U console in an app-misc/screen session
system-qemu Using app-emulation/qemu instead of the bundled one
system-seabios Using sys-firmware/seabios instead of the bundled one

xtrs

ls-dos Install LS-DOS disk images for Model 4P

app-eselect

eselect-php

fpm Enable the FastCGI Process Manager SAPI

app-forensics

afflib

fuse Enable extra fuse thingies
qemu Enable qemu stuff
s3 Enable support for Amazon S3

aide

audit Enable support for sys-process/audit
prelink Enable support for sys-devel/prelink

chkrootkit

cron Install cron script for weekly rootkit scans

libewf

bfio Enables libbfio for chaining file in file handling
ewf Enables the v1 API
fuse Enable fuse support for ewfmount
rawio Enables raw IO handling
uuid Enable UUID support in the ewftools

openscap

gconf Build the gconf independant probes
nss Prefer NSS over libgcrypt as the crypto engine
rpm Compiles the RPM probes
sce Enables Script Check Engine (SCE) support
sql Build the sql independant probes

ovaldi

rpm Enable the RPM probes

sleuthkit

aff Enable extra aff formats
ewf Enable libewf support

app-i18n

anthy

canna-2ch Enable support for app-dicts/canna-2ch

fcitx

autostart Enable xdg-compatible autostart of fcitx
enchant Use app-text/enchant for text prediction
gtk Install GTK2 IM module
gtk3 Install GTK3 IM module
introspection Enable GObject Introspection
opencc Enable OpenCC for Chinese Transform
pango Enable support for x11-libs/pango
qt4 Install Qt4 IM module
snooper Enable Key Snooper for GTK app
table Enable Table IM

fcitx-configtool

gtk3 Use GTK+3 instead of 2

fcitx-libpinyin

dictmanager Enable dictionary manager. Requires dev-qt/qtwebkit.

ibus

deprecated install the deprecated ibus python library
gconf Enable support for gnome-base/gconf
gtk3 Enable support for gtk+3
introspection Use dev-libs/gobject-introspection for introspection
vala Enable support for dev-lang/vala

ibus-anthy

deprecated Install deprecated pygtk2 library

ibus-handwrite

zinnia Build with app-i18n/zinnia engine.

ibus-libpinyin

boost Compile against dev-libs/boost libraries
opencc Enable support for app-i18n/opencc

ibus-m17n

gtk Build the preference interfaces, based on x11-libs/gtk+ (GTK+ 2).

ibus-pinyin

boost Compile against dev-libs/boost libraries
opencc Enable support for app-i18n/opencc

ibus-unikey

gtk3 Enable support for gtk+3

im-ja

anthy Support for Anthy input method
skk Support for SKK input method

imsettings

gconf Enable GConf support
gtk3 Enable support for x11-libs/gtk+:3
xfconf Enable integration in the Xfce desktop environment with xfce-base/xfconf

kimera

anthy Support for Anthy input method

libskk

introspection Use dev-libs/gobject-introspection for introspection

libtomoe-gtk

gucharmap Enable gucharmap dictionary plugin

mozc

fcitx Enable support for app-i18n/fcitx
ibus Enable support for app-i18n/ibus
renderer Enable native candidate window.

pyzy

boost Enable support for dev-libs/boost
doc Enable support for documents
opencc Use app-i18n/opencc for input

scim

gtk3 Enable support for x11-libs/gtk+:3

scim-anthy

gtk3 Enable support for x11-libs/gtk+:3
kasumi Use Anthy dictionary maintenance tool (app-dicts/kasumi)

scim-tomoe

gucharmap Enable gucharmap dictionary plugin

tomoe

hyperestraier Enable support for app-text/hyperestraier

uim

anthy Enable support for app-i18n/anthy input method
eb Enable support for dev-libs/eb
gtk3 Enable support for x11-libs/gtk+:3
skk Enable support for app-i18n/skk-jisyo

app-laptop

hdapsd

libconfig Require dev-libs/libconfig to allow the daemon to read a configuration file at startup

ibam

gkrellm Enable building of app-admin/gkrellm module

laptop-mode-tools

scsi Adds dependency on sdparm to control non-SATA SCSI drivers

pbbuttonsd

ibam Enable support for Intelligent Battery Monitoring
macbook Enable support for the Macbook and Macbook Pro

prey

alarm Module for playing an audio file
alert Display a warning message when the computer seems to be stolen"
geo Module for retrieving the physical location of the stolen computer
lock Lock stolen computer
network Get network information (active connections, traceroute) from stolen computer
secure Delete or hide sensitive user data
session Get screenshots from user session
userpriv Create a prey user group so regular users can access and modify the prey configuration. Use it with caution
webcam Use computer's webcam to take screenshots of the thief

thinkfan

atasmart include libatasmart support to get disc temperature

tp_smapi

hdaps Install a compatible HDAPS module

app-leechcraft

lc-aggregator

webaccess Enables web interface submodule for Aggregator

lc-azoth

acetamide Build Acetamide, the IRC protocol support
adiumstyles Build support for Adium styles
astrality Build Astrality, support for protocols provided by Telepathy
autoidler Build support for automatic status changing according to user idle time
autopaste Build Autopaste for pasting long texts to pastebins
birthdaynotifier Build Birthday Notifier for you to not forget about birthdays of your contacts.
chathistory Build ChatHistory which stories chat history
depester Build Depester which enables to ignore MUC participants
embedmedia Build EmbedMedia for embedding flash videos and images directly into chat windows
herbicide Build Herbicide, a basic antispam plugin
hili Build HiLi which allows to customize highlight settings in MUCs
isterique Build Isterique plugin for neutralizing excessive caps lock usage
juick Build plugin for the Juick.com microblogging service
keeso Build plugin for changing text into SoMEtHInG lIKe THiS
lastseen Build plugin for client-side recording of the last online/available time
media Enable media calls
metacontacts Build plugin for metacontacts support
murm Build Murm, the VKontakte messaging support via their native API (instead of XMPP)
nativeemoticons Build support for native Azoth's emoticons packs
otroid Build OTRoid, plugin for the Off-the-Record deniable encryption system
p100q Build p100q, plugin for psto.net microblogging service
sarin Build Sarin, Tox protocol support module. Please add mva overlay to use net-libs/tox
shx Build shell command executor plugin
standardstyles Build support for standard Azoth styles engine
vader Bulid Vader, the MRIM (Mail.Ru Agent) protocol support plugin
velvetbird Build support for protocols provided by libpurple
woodpecker Build Woodpecker, the Twitter client plugin
xtazy Build Xtazy for publishing currently playing tune

lc-blasq

deathnote Support LiveJournal FotoBilder service
rappor Support VKontakte service
spegnersi Support Flickr service
vangog Support Picasa service

lc-blogique

hestia Allows one to keep a local blog
metida Support for the LiveJournal blogging platform

lc-core

qwt Support for QML plotting item through x11-libs/qwt

lc-gmailnotifier

notify Pull in a plugin to show notifications from GMail Notiifer
quark Pull in a plugin to show GMail Notifier's quark

lc-liznoo

systemd Pull in correct UPower dependencies for systemd and non-systemd users.

lc-lmp

fradj Build FrAdj, the equalizer effect module
graffiti Build media tags editor plugin
guess Enable tags encoding guessing via the libguess library
mp3tunes Build plugin for supporting the mp3tunes.com music locker service
mpris Enable MPRIS support
potorchu Enable the projectM-based visualization effects module for LMP

lc-monocle

fb2 Enable support for FictionBook format
mobi Enable support for MOBI format
spectre Enable PostScript backend for Monocle using the app-text/libspectre

lc-musiczombie

acoustid Use media-libs/chromaprint for acoustic fingerprinting

lc-netstoremanager

googledrive Support Google Drive storage backend
yandexdisk Support Yandex.Disk storage backend

lc-poshuku

autosearch Provide automatic search suggestions for Poshuku.
cleanweb Build CleanWeb for ad blocking compatible with Firefox's AdBlock+.
dcac Build color inverter module providing a night mode.
fatape Build FatApe, GreaseMonkey userscripts support layer.
filescheme Build FileScheme for accessing local URLs.
fua Build FUA for faking user agents for different hosts.
keywords Build Keywords for adjusting search shortcuts.
onlinebookmarks Build OnlineBookmarks for syncing bookmarks with social bookmarking services like Read It Later.
pcre Use dev-libs/libpcre for rules matching in CleanWeb instead of slower QRegExp.
qrd Build module for displaying the QR code of a web page.
wyfv Build WYFV for replacing Flash-based video players on some sites.

leechcraft-meta

de Install components, that allow using Leechcraft as Desktop Environment

app-misc

anki

recording Enable support for audio recording
sound Enable support for adding sound to cards

binwalk

graph Enable support for generating entropy graphs

brewtarget

phonon Enable sound support via media-libs/phonon or dev-qt/qtphonon

byobu

screen Use app-misc/screen as the default backend

ca-certificates

cacert Include root certs from CAcert (http://www.cacert.org/) and Software in the Public Interest (http://www.spi-inc.org/)

ddccontrol

pci enable direct PCI memory access (the setuid ddcpci util)

digitemp

ds2490 Build support for the ds2490 sensor
ds9097 Build support for the ds9097 sensor
ds9097u Build support for the ds9097u sensor

emelfm2

ansi Add support for ANSI escape sequences
gtk3 Use x11-libs/gtk:3 instead of x11-libs/gtk:2

freemind

groovy Build plugin for scripting via Groovy
latex Build plugin for inserting mathematical formulas in LaTeX syntax
pdf Build plugin for exporting mindmaps to SVG and PDF
svg Build plugin for exporting mindmaps to SVG and PDF

gcstar

stats Enable statistics reporting
tellico Enable support for kde-misc/tellico files

geneweb

ocamlopt Enable ocamlopt support (dev-lang/ocaml native code compiler)

geoclue

geonames Install geonames.org provider
gsmloc Install GSM location provider
gtk Install gtk-based geoclue-test-gui
hostip Install hostip.info provder
manual Install manual provider
modemmanager Enable geolocation through 3G or GPS enabled hardware through net-misc/modemmanager.
nominatim Install openstreetmap.org provider
plazes Install plazes.com provider
skyhook Install skyhookwireless.com provider
yahoo-geo Install Yahoo geolocation provider

gourmet

i18n >app-misc/gourmet-0.16 Enable support for i18n through elib.intl
ipython >app-misc/gourmet-0.16 Enable support for the interactive Python console plugin
pdf Enable export to PDF
print >app-misc/gourmet-0.16 Enable pretty Python printing
spell >app-misc/gourmet-0.16 Enable support for the spell check plugin
web >app-misc/gourmet-0.16 Enable support for the web import plugin

gramps

reports All external software that is needed for graphical reports will be installed
webkit Use Webkit-based rendering for geographical data view.

graphlcd-base

g15 Add support for app-misc/g15daemon driver (e.g. Logitech G15 Keybord)

irtrans-irserver

mono Enable mono support

lcd-stuff

mpd Add support for display of mpd controlled music (media-libs/libmpd)

lcd4linux

mpd Add support for display of mpd controlled music (media-libs/libmpd)

lcdproc

ftdi Enable support for FTDI connections in some selected LCD_DEVICES (currently hd44780)
hid Enable HID support using libhid
irman Enable support for IRMan (media-libs/libirman)
lcd_devices_sdeclcd Enable support for VLSYS M428 display
lcd_devices_vlsys_m428 Enable support for VLSYS M428 display
nfs Adds support for NFS file system
seamless-hbars Try to avoid gaps in horizontal bars
nls Add Native Language Support (using gettext - GNU locale utilities)

lirc

hardware-carrier The transmitter device generates its clock signal in hardware
transmitter Add transmitter support to some lirc-drivers (e.g. serial)

mc

edit Compile and install the mcedit application
mclib Compile and install the libmc.so shared library
sftp Add support for sftp (uses net-libs/libssh2 for it).
slang Use sys-libs/slang instead of sys-libs/ncurses.
xdg Toggles mc's config dir location. Enable for $XDG_CONFIG_HOME/mc, disable for $HOME/.mc

muttprint

doc Builds documentation

note

general Add support for ascii flatfile backend
text Add support for text backend

pax-utils

python Install a more powerful/faster version of lddtree

recoll

camelcase Enable indexing for camelCase sentences and words
chm Index chm files
dvi Index dvi files
ics Index iCalendar files
info Index GNU info files
inotify Use the Linux Kernel notification subsystem for monitoring file alterations in realtime
lyx Index Latex lyx files
msdoc Index Microsoft Word documents
msppt Index Microsoft PowerPoint documents
msxls Index Microsoft Excel documents
pdf Index PDF documents
rtf Index Microsoft RTF documents
session Stop monitoring file alterations when X11 session terminates
sound Index audio files
tex Index TeX files
wordperfect Index WordPerfect documents
xml Index several XML-based formats (Abiword, FictionBook, Kword, Office OpenXML, OpenDocument, SVG)

rlwrap

debug Enable debug

roadnav

festival Enable support for app-accessibility/festival
openstreetmap Enable openstreetmap support
scripting Enable scripting support

screen

multiuser Enable multiuser support (by setting correct permissions)
nethack Express error messages in nethack style

screenfetch

X Use the media-gfx/scrot package to take screenshots

sphinx

id64 use 64-bit document and word IDs
stemmer Enable language stemming support

strigi

clucene Enable dev-cpp/clucene backend support.
inotify Enable support for inotify.
log Enables advanced logging through dev-libs/log4cxx.

subsurface

linguas_da_DK Language support for da_DK.
linguas_de_CH Language support for de_CH.
linguas_gsw Language support for gsw.
linguas_hr_HR Language support for hr_HR.

tablix

pvm Add support for parallel virtual machine (sys-cluster/pvm)

tasque

hiveminder Allows you to use http://www.hiveminder.com/ as your storage backend.
rememberthemilk Allows you to use http://www.rememberthemilk.com/ as your storage backend.

towitoko

moneyplex Makes libtowitoko work for the moneyplex home banking software

tracker

cue Enable cue sheet parsing
firefox-bookmarks Install bookmark data miner plugin for www-client/firefox and www-client/firefox-bin
gsf Enable gnome-extra/libgsf based data extractor and for ODT.
iptc Enable extraction of IPTC data from pictures
iso Enable extraction of metadata from ISO disk images
miner-fs Enable tracker-miner-fs (required for filesystem indexing)
nautilus Enable tracker to integrate with gnome-base/nautilus by providing entries in its context menu
playlist Add support for playlists
stemmer Add word stemming via dev-libs/snowball-stemmer.
thunderbird Install email data miner plugin for mail-client/thunderbird and mail-client/thunderbird-bin
xps Add support for XPS file format through app-text/libgxps.

unfoo

minimal Do not install all support archive binaries

vifm

X Add support for X11
compatibility Compatibility with previous versions of vifm
developer Enable features of interest to developers
extended-keys Support for extended keys (arrows, home etc)
gtk Use gtk+ to determine mimetypes
magic Use libmagic to determine mimetypes
vim Install the vifm vim plugin and vim-compatible documentation
vim-plugin Install the vifm vim plugin
vim-syntax Pulls in related vim syntax scripts

worker

avfs Enable support for sys-fs/avfs
magic Add magic file support from sys-apps/file to automatically detect file types

workrave

distribution Enable networking. See http://www.workrave.org/features/
mate Add support for MATE panel
xfce Add support for XFCE panel

zygrib

maps Installs additional GSHHS maps for high resolution coastline data and cities

app-mobilephone

gammu

irda Enables infrared support

gnokii

ical Enable support for dev-libs/libical
irda Enable infrared support
pcsc-lite Enable smartcard support with sys-apps/pcsc-lite
sms Enable SMS support (build smsd)

obexd

nokia Add support for Nokia backup plugin
server Enables server installation, it's incompatible with obex-data-server provided one

smstools

stats Enable statistic reporting

yaps

capi Enable CAPI support

app-office

abiword

collab Enable collaborative editing plugin
goffice Enable goffice plugin
grammar Enable grammar checking via dev-libs/link-grammar
map Enable world map support through media-libs/libchamplain
math Enable support for x11-libs/gtkmathview
ots Enable Text Summarizer plugin
plugins Enable plugins build (see http://www.abisource.com/wiki/PluginMatrix for more information). If your file cannot be opened due lack of support, try enabling this.
redland Enables support redland and raptor libs.
thesaurus Enable thesaurus support
wordperfect Enable wordperfect file support via app-text/libwpd

akonadi-server

soprano Enable deprecated dev-libs/soprano, needed for nepomuk search

calligra

attica Get hot stuff with dev-libs/libattica
eigen Enable dev-cpp/eigen mathematical templates support
glew Enable media-libs/glew opengl extension library support
glib Enable support for C library routines from dev-libs/glib
gsf Enable support for ODT structures extraction via gnome-extra/libgsf
import-filter Enable support for various import filter file formats like WordPerfect, Visio and Apple Keynote
kdcraw Enable support for KDE image manipulating interface via kde-apps/libkdcraw
kdepim Enable support for KDEPIM resources integration
marble Enable displaying of maps using Marble
nepomuk Enable Nepomuk based semantic desktop support (deprecated)
okular Enable bindings for kde-apps/okular
spacenav Enable support for the 3Dconnexion spacenav input device via dev-libs/libspnav
vc Enable support for dev-libs/vc, could be a significant speed boost on krita
xbase Enable support for xbase compatible database formats

glabels

barcode Enable barcode support through external libraries.

gnucash

chipcard Enable support for chipcard reading and processing.
hbci Enable HBCI support, for connecting to some internet banks
quotes Enable Online Stock Quote retrieval

gnumeric

libgda Enable database support through gnome-extra/libgda.
perl Enable perl plugin loader.
python Enable python plugin loader.

kmymoney

hbci Enable HBCI support using net-libs/aqbanking
quotes Enable Online Stock Quote retrieval

libreoffice

coinmp Use sci-libs/coinor-mp as alternative solver
collada Enable Collada for rendering 3D models stored in *.dae and *.kmz format
gltf Use media-libs/libgltf for inserting 3D models in the glTF format into presentations
gtk3 Enable highly experimental gtk3 frontend
jemalloc Use dev-libs/jemalloc for allocations
odk Build the Office Development Kit
telepathy Enable document colaboration features using telepathy communication framework.
vlc Use media-video/vlc for video embedding

libreoffice-l10n

linguas_ca_valencia Catalan locale (Valencia)
linguas_kmr_Latn kmr_Latn localization
linguas_sid sid localization
linguas_sr_Latn Serbian (Latin) locale
offlinehelp Install help files locally instead of using the LibreOffice Wiki

lyx

aspell Add support for aspell spellchecking
dia Add support for diagrams (app-office/dia)
docbook Add support for docbook export
dot Add support for DOT import (media-gfx/graphviz)
enchant Add support for enchant spellchecking wrapper (both aspell and hunspell can be used by LyX).
gnumeric Add support for importing Gnumeric/OpenOffice/MS Excel spreadsheets into LyX.
html Add support for HTML import
hunspell Add support for spellchecking based on hunspell and reuse system-wide OpenOffice dictionaries. This also enable thesaurus dictionaries not accessible via aspell.
monolithic-build This should speed up compilation significantly when you have enough RAM (> 600 MB)
rcs Add support for revision control via dev-vcs/rcs
rtf Add support for RTF import/export packages

scribus

boost Enable support for Boost based enhancement
graphicsmagick Add support for media-gfx/graphicsmagick
hunspell Enable support for spell checking with app-text/hunspell
minimal Don't install headers (only required for e.g. plug-in developers)
osg 3D redering via dev-games/openscenegraph
scripts Install the scripts
templates Document tamplates
tk Install tk based scripts e.g. FontSample.py

skrooge

activities Enable kactivities support

texmacs

netpbm Add support for media-libs/netpbm
pdf Add the experimental native pdf export

texstudio

video Use phonon for video embedding

wps-office

corefonts Ensure media-fonts/corefonts is present
sharedfonts Preserve fonts from WPS

app-pda

barry

boost Enable boost support
desktop Install the GUI desktop control panel
gui Install the GUI backup tool
opensync Install the barry-sync plugin for OpenSync 0.22

gtkpod

clutter Enable clutter support for displaying coverart
webkit Enable webkit support for finding coverart

libopensync-plugin-irmc

irda Enable infrared support

libopensync-plugin-syncml

http Enable http transports
obex Enable obex transports

libsyncml

http Enable http transports
obex Enable obex transports

synce-sync-engine

opensync Enable OpenSync (app-pda/libopensync) python plug-in

app-portage

conf-update

colordiff Use colors when displaying diffs (app-misc/colordiff)

eix

debug Build with upstream's CXXFLAGS/LDFLAGS for debugging support; not recommended for normal use.
dep Make DEP=true the default which enables support for {,R,P}DEPEND but requires roughly double disk and memory.
doc Create description of the eix cache file additionally in html format
optimization Accept upstream's choices for CXXFLAGS/LDFLAGS for optimization. Absense of this USE flag does not strip user's *FLAGS
security This adds some checks which can prevent certain exploits if e.g. the eix code has a bug. If you use the hardened toolchain, using this flag does not increase security and can even lead to problems.
sqlite Compile in support for portage's sqlite backend; to actually use it you need additional configuration of portage and eix
strong-optimization Adds several more agressive CXXFLAGS/LDFLAGS for optimization like graphite (if available). May cause trouble with some buggy compiler versions. Absense of this USE flag does not strip user's *FLAGS
strong-security Add many checks to prevent exploits if eix code has a bug. This will slow down eix considerably. Use only if you are paranoid or have reasons to suspect a bug.
swap-remote Swap role of remote addresses in eix-remote, making the data from gpo.zugaina.org the first choice.
tools Create separate binary for script helper tools; useful if they are called extremely often

g-sorcery

bson Support BSON file format for package DB

layman

bazaar Support dev-vcs/bzr based overlays
cvs Support dev-vcs/cvs based overlays
darcs Support dev-vcs/darcs based overlays
g-sorcery Support app-portage/g-sorcery based overlays
git Support dev-vcs/git based overlays
gpg Support app-crypt/gnupg signed overlays lists and manifests
mercurial Support dev-vcs/mercurial based overlays
squashfs Support mounting squashfs image overlays locally read-only
subversion Support dev-vcs/subversion based overlays
sync-plugin-portage Install the sys-apps/portage sync module

pfl

network-cron Adds a cron job which does a weekly submit of the package database

tatt

templates Install template scripts to be used with tatt

app-shells

bash

bashlogger Log ALL commands typed into bash; should ONLY be used in restricted environments such as honeypots
mem-scramble Build with custom malloc/free overwriting allocated/freed memory
net Enable /dev/tcp/host/port redirection
plugins Add support for loading builtins at runtime via 'enable'

pdsh

rsh This allows the use of rsh (remote shell) and rcp (remote copy) for authoring websites. sftp is a much more secure protocol and is preferred.

scsh-install-lib

scsh Use a non-FHS directory layout

shish

diet Use dev-libs/dietlibc

tcsh

catalogs Add support for NLS catalogs

app-text

acroread

html HTML support and help reading capability (only for x86).

apvlv

html Build binary with html format support

asciidoc

highlight Enable source code highlighting

atril

caja Enable property page extension in mate-base/mate-file-manager
dvi Enable build-in DVI viewer
ps Enable build-in postscript viewer
t1lib Enable the Type-1 fonts for the build-in DVI viewer (media-libs/t1lib)
xps Enable XPS viewer using app-text/libxps

crm114

mew Add support for using the mewdecode mime decoder (app-emacs/mew)
mimencode Add support for using the mimencode mime (net-mail/metamail)
normalizemime Add support for using the normalizemime (mail-filter/normalizemime)

cuneiform

graphicsmagick Enables support of various input formats using media-gfx/graphicsmagick. Otherwise only uncompressed BMP files are supported.
imagemagick Enables support of various input formats using media-gfx/imagemagick. Otherwise only uncompressed BMP files are supported.

dbacl

interactive Enable the interactive mailinspect ability

dictd

judy Build Judy-based (dev-libs/judy) plugin implementing fast "exact" and especially "lev" strategies
minimal Don't build server but dict client, dictzip and dictfmt only.

docbook-sgml-utils

jadetex Add support for app-text/jadetex (for processing tex files produced by the TeX backend of Jade)

docbook-xsl-ns-stylesheets

ruby Install the Ruby-based dbtoepub script; requires an interpreter compatible with app-eselect/eselect-ruby.

docbook-xsl-stylesheets

ruby Install the Ruby-based dbtoepub script; requires an interpreter compatible with app-eselect/eselect-ruby.

dvipng

t1lib Enable support for T1lib font rendering (media-libs/t1lib)

enchant

aspell Adds support for app-text/aspell spell checker
hunspell Adds support for app-text/hunspell spell checker
zemberek Adds support for app-text/zemberek-server spell checker server

evince

dvi Enable the built-in DVI viewer
libsecret Enable support for credentials store
nautilus Enable property page extension in gnome-base/nautilus
t1lib Enable the Type-1 fonts for the built-in DVI viewer (media-libs/t1lib)
xps Enable XPS viewer using app-text/libgxps

getxbook

ocr Use app-text/tesseract for optical character recognition

glark

zip Support for ZIP files using dev-ruby/rubyzip

groonga

abort Enable query abortion
benchmark Build benchmark programs
dynamic-malloc-change Allow dynamic memory allocation change for testing
exact-alloc-count Atomic counting for memory alloc count
fmalloc Make memory allocation failed in specified condition for debug
futex Use futex
libevent Enable dev-libs/libevent used for suggestion
mecab Use app-text/mecab for morphological analysis
msgpack Enable dev-libs/msgpack used for suggestion
nfkc Use nfkc based utf8 normalization
sphinx Enable document generation by app-misc/sphinx
uyield Build for detecting race conditions
zeromq Enable net-libs/zeromq used for suggestion

gtkspell

vala Enable bindings for dev-lang/vala

hyperestraier

mecab Enable app-text/mecab support for Estraier

jmupdf

system-mupdf Link against system version of app-text/mupdf

lcdf-typetools

kpathsea Enable integration with kpathsea search library (TeX related)

liblangtag

introspection Use dev-libs/gobject-introspection for introspection

libwpd

tools Build miscellaneous tools

lodgeit

vim Install a vim plugin allowing to paste and download from within vim

mathtex

png Generate png images by default instead of gif

mupdf

openssl Use dev-libs/openssl crypto backend

pandoc

embed_data_files Embed data files in binary for relocatable executable.
http-conduit Enable downloading of resources over https.
https Enable support for downloading of resources over https.
make-pandoc-man-pages Build program to regenerate pandoc man pages from README.
network-uri Get Network.URI from the network-uri package.
trypandoc Build trypandoc cgi executable.

pastebinit

crypt Install pbputs for gpg-encrypted pastes

pdf2djvu

graphicsmagick Enable media-gfx/graphicsmagick support

pdfgrep

unac Removing accents and ligatures before search

pelican

markdown Markdown support

podofo

boost Add support for boost

poppler

introspection Enable GObject introspection.
utils Install command-line PDF converters and various utilities.

qpdfview

fitz Use experimental fitz rendering, provided by app-text/mupdf, instead of poppler
synctex Add support for searching TeX sources

sgmltools-lite

jadetex Add support for app-text/jadetex (for processing tex files produced by the TeX backend of Jade)

stardict

espeak Enable text to speech synthesizer using espeak engine
gucharmap Enable gucharmap dictionary plugin
pronounce Install WyabdcRealPeopleTTS package (it is just many .wav files) to make StarDict pronounce English words
qqwry Enable QQWry plugin, which provides information (in Chinese language) about geographical positions, owner, etc. for IP addresses
tools Build and install the extra stardict tools

tesseract

linguas_chr Enable support for the Cherokee language.
linguas_jp Enable support for Japanese.
opencl Enable opencl support for speedup using GPU computation.
osd Enable support orientation and script detection.
scrollview Enable graphics support (ScrollView).
webp Enable support for webp image format.

texlive

context Add support for the ConTeXt format (dev-texlive/texlive-context)
detex Add support for dev-tex/detex, a filter program that removes the LaTeX (or TeX) control sequences
dvi2tty Add support for dev-tex/dvi2tty to preview dvi-files on text-only devices
dvipdfm Add support for app-text/dvipdfm to convert DVI files to PDF
epspdf Add support for app-text/epspdf, a tool for converting [e]ps files to pdf.
extra Add support for extra TeXLive packages
games Add typesetting support for games (chess, etc.) (dev-texlive/texlive-games)
graphics Add support for several graphics packages (pgf, tikz,...)
humanities Add LaTeX support for the humanities (dev-texlive/texlive-humanities)
jadetex Add support for app-text/jadetex (for processing tex files produced by the TeX backend of Jade)
luatex Add extra support for luatex
metapost Add support for metapost: A tool for creating graphics in scalable PostScript.
music Add support for music typesetting (dev-texlive/texlive-music)
omega Add omega packages (dev-texlive/texlive-omega)
pdfannotextractor Add dev-tex/pdfannotextractor support, for extracting annotations from PDF files.
pstricks Add pstricks packages (dev-texlive/texlive-pstricks)
publishers Add support for publishers (dev-texlive/texlive-publishers)
science Add typesetting support for natural and computer sciences (dev-texlive/texlive-science)
tex4ht Add support for dev-tex/tex4ht (for converting (La)TeX to (X)HTML, XML and OO.org)
texi2html Add support for app-text/texi2html which converts texi files to HTML.
xetex Add support for XeTeX macros (dev-texlive/texlive-xetex)
xindy Add support for app-text/xindy, a flexible indexing system

texlive-core

xetex Add support for XeTeX: a TeX system with Unicode and modern font technologies.

wdiff

experimental Build experimental utilities (mdiff, unify, wdiff2)

webgen

builder Enable programmatic HTML/XML generation
highlight Enable syntax highlighting for certain plugins
markdown Markdown support

wgetpaste

lodgeit-default Set one of lodgeit-like (ex http://paste.pocoo.org) services as default

wklej

vim Install the vim plugin allowing to paste through ':Wklej'.

writerperfect

abiword Add support for abiword format using app-text/libabw
ebook Add support for various ebook formats using app-text/libebook
freehand Add support for freehand format using media-libs/libfreehand
gsf Add support for structured files using gnome-extra/libgsf
keynote Add support for keynote format using app-text/libetonyek
mspub Add support to mspub format using app-text/libmspub
mwaw Add support to mwaw formats using app-text/libmwaw
pagemaker Add support to pagemaker formats using media-libs/libpagemaker
visio Add support for visio format using media-libs/libvisio
wpd Add support for wpd format using app-text/libwpd
wpg Add support for wpg format using app-text/libwpg
wps Add support for wps format using app-text/libwps

wv

tools Install optional utilities considered deprecated in favor of using AbiWord.

xiphos

webkit Use net-libs/webkit-gtk instead of gnome-extra/gtkhtml

yagf

cuneiform Enable support for the app-text/cuneiform OCR engine.
tesseract Enable support for the app-text/tesseract OCR engine.

zathura

magic Use libmagic to determine mimetypes

zathura-meta

cb Install plug-in for ComicBook support

app-vim

gentoo-syntax

ignore-glep31 Remove GLEP 31 (UTF-8 file encodings) settings

vim-latex

html Install HTML documentation
python Enable python support which can help speed up some functionality

youcompleteme

clang Enable semantic support for C-family languages using sys-devel/clang

dev-cpp

glog

gflags Use dev-cpp/gflags for flag parsing
unwind Use sys-libs/libunwind for stack unwinding instead of glibc/gcc (may be more reliable on x86_64)

libcmis

man Build and install man pages.

libjson-rpc-cpp

http-client Build support for HTTP client using dev-util/curl
http-server Build support for HTTP server using net-libs/libmicrohttpd
stubgen Build header stub code generator (needed for development and when pregenerated headers are not bundled)

pficommon

fcgi Build FCGI feature
mprpc Build MessagePack RPC feature

websocketpp

boost Use dev-libs/boost instead of C++11

xsd

ace Enable support for serializing to/from an ACE CDR stream

dev-db

cppdb

mysql_internal Don't build a separate mysql loadable module but rather build it into the cppdb library itself
odbc_internal Don't build a separate postgresql loadable module but rather build it into the cppdb library itself
postgres_internal Don't build a separate odbc loadable module but rather build it into the cppdb library itself
sqlite_internal Don't build a separate sqlite3 loadable module but rather build it into the cppdb library itself

drizzle

curl Enable the HTTP authentication plugin (using net-misc/curl). This is needed for the tests to apply properly.
doc Build the API documentation for the package, using app-doc/doxygen. Warning, this might take over an hour on slower machines.
gearman Enable the gearman plugins for user-defined functions and logging (using sys-cluster/gearman).
md5 Enable the MD5 plugin, using dev-libs/libgcrypt; this replaces the older openssl and gnutls USE flags.
memcache Enable the memcache plugin for user-defined functions and statistics in I_S tables (using dev-libs/libmemcached). Currently restricts tests because of an upstream testsuite bug.
pam Enable the PAM authentication plugin (using sys-libs/pam). The configuration file created will be /etc/pam.d/drizzle.
v8 Use dev-lang/v8.

firebird

client Install client library and header files only
superserver Install SuperServer
xinetd Install ClassicServer

haildb

debug Enable extra debug codepaths and assertions. If disabled, both the debug code and assertions are removed from the resulting binaries. Optimisations are untouched.
zlib Add support for compressed tables through sys-libs/zlib.

maatkit

udf Build the MySQL UDFs shipped with maatkit, requires non-minimal MySQL

mariadb

client-libs Build the libmysqlclient libraries
cluster Add support for NDB clustering (deprecated)
community Enables the community features from upstream.
embedded Build embedded server (libmysqld)
extraengine Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jemalloc Use dev-libs/jemalloc for allocations.
latin1 Use LATIN1 encoding instead of UTF8
max-idx-128 Raise the max index per table limit from 64 to 128
minimal Install client programs only, no server
oqgraph Add support for the Open Query GRAPH engine
pam Enable the optional PAM authentication plugin for the server
profiling Add support for statement profiling (requires USE=community).
server Build the server program
sphinx Add suport for the sphinx full-text search engine
systemtap Build support for profiling and tracing using dev-util/systemtap
test Install upstream testsuites for end use.
tokudb Add support for TokuDB storage engine
tools Build the command line tools (mysql, mysqldump, mysqladmin, etc)

mariadb-galera

client-libs Build the libmysqlclient libraries
cluster Add support for NDB clustering (deprecated)
community Enables the community features from upstream.
embedded Build embedded server (libmysqld)
extraengine Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jemalloc Use dev-libs/jemalloc for allocations.
latin1 Use LATIN1 encoding instead of UTF8
minimal Install client programs only, no server
oqgraph Add support for the Open Query GRAPH engine
profiling Add support for statement profiling (requires USE=community).
server Build the server program
sphinx Add suport for the sphinx full-text search engine
sst-rsync Add tools needed to support the rsync SST method
sst-xtrabackup Add tools needed to support the xtrabackup and xtrabackup-v2 SST methods
systemtap Build support for profiling and tracing using dev-util/systemtap
test Install upstream testsuites for end use.
tokudb Add support for TokuDB storage engine
tools Build the command line tools (mysql, mysqldump, mysqladmin, etc)

mongodb

mms-agent Install the MongoDB Monitoring Service agent
sharedclient build client shared library libmongoclient.so
spidermonkey Use embedded SpiderMonkey engine (dev-lang/spidermonkey) instead of v8
tools Install the MongoDB tools (mongoimport, mongodump...) from app-admin/mongo-tools

mysql

client-libs Build the libmysqlclient libraries
cluster Add support for NDB clustering (deprecated)
community Enables the community features from upstream.
embedded Build embedded server (libmysqld)
extraengine Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jemalloc Use dev-libs/jemalloc for allocations.
latin1 Use LATIN1 encoding instead of UTF8
max-idx-128 Raise the max index per table limit from 64 to 128
minimal Install client programs only, no server
profiling Add support for statement profiling (requires USE=community).
server Build the server program
systemtap Build support for profiling and tracing using dev-util/systemtap
test Install upstream testsuites for end use.
tools Build the command line tools (mysql, mysqldump, mysqladmin, etc)

mysql-cluster

cluster Add support for NDB clustering
community Enables the community features from upstream.
embedded Build embedded server (libmysqld)
extraengine Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jemalloc Use dev-libs/jemalloc for allocations.
latin1 Use LATIN1 encoding instead of UTF8
max-idx-128 Raise the max index per table limit from 64 to 128
minimal Install client programs only, no server
profiling Add support for statement profiling (requires USE=community).
systemtap Build support for profiling and tracing using dev-util/systemtap
test Install upstream testsuites for end use.

mysql-connector-c++

gcov Build coverage support

percona-server

client-libs Build the libmysqlclient libraries
cluster Add support for NDB clustering (deprecated)
community Enables the community features from upstream.
embedded Build embedded server (libmysqld)
extraengine Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jemalloc Use dev-libs/jemalloc for allocations.
latin1 Use LATIN1 encoding instead of UTF8
minimal Install client programs only, no server
profiling Add support for statement profiling (requires USE=community).
server Build the server program
systemtap Build support for profiling and tracing using dev-util/systemtap
test Install upstream testsuites for end use.
tools Build the command line tools (mysql, mysqldump, mysqladmin, etc)

pgadmin3

databasedesigner Enable the Database Designer component

pgbouncer

libevent Use libevent 2.0+ and evdns as the DNS backend
udns Use udns as the DNS backend. Supports IPv4 only.

pgpool2

memcached Use memcached for query caching.

pgrouting

drivingdistance Enable to calculate driving distance
html Install HTML formatted documentation

phpmyadmin

setup Installs the phpMyAdmin setup utility. Users who don't use the utility should disable this USE flag for security reasons as the setup tool was the target of various exploits in the past.

postgis

gtk Build shp2pgsql-gui a graphical interface to shp2pgsql

postgresql

pg_legacytimestamp Use double precision floating-point numbers instead of 64-bit integers for timestamp storage.
server Disable to build and install the clients and libraries only.
uuid Enable server side UUID generation (via dev-libs/ossp-uuid).

psqlodbc

iodbc Use dev-db/libiodbc. Disable to use dev-db/unixODBC.

recutils

curl Enable support for remote descriptors using libcurl
mdb Build the mdb2rec utility
uuid Enable support for uuid types

redis

jemalloc Use dev-libs/jemalloc for allocations.
tcmalloc Use tcmalloc from dev-util/google-perftools for allocations.

soci

boost Enable boost support
empty Build the sample backend called Empty

spatialite

geos Add the sci-libs/geos library for exact topological tests
proj Add the sci-libs/proj library for reprojection features
xls Add the dev-libs/freexl library for xls import support

sqlite

secure-delete Enable overwriting of deleted content with zeros by default (http://sqlite.org/pragma.html#pragma_secure_delete), causing some performance penalty
tools Install additional tools

tokumx

pax_kernel Apply patch needed for hardened kernels

unixODBC

minimal Disable bundled drivers and extra libraries (most users don't need these)
odbcmanual Administrator, Internal Structure, Programmer and User documentation

dev-embedded

avrdude

ftdi Enable support for USB FTDI chips via dev-embedded/libftdi

libftdi

tools build ftdi_eeprom helper tool

openocd

blaster Enable support for Altera USE-Blaster
cmsis-dap Support for CMSIS-DAP compliant adapters
dummy Build the dummy port driver
ftd2xx Enable support for USB FTDI chips via dev-embedded/libftd2xx
ftdi Enable support for USB FTDI chips via dev-embedded/libftdi
minidriver Build the dummy minidriver
parport Enable support for parport JTAG devices
presto Enable support for AXIS PRESTO devices
segger Enable support for the Segger J-Link JTAG
stlink Enable building support for the ST-Link JTAG Programmer
verbose-io Verbose IO and comm JTAG and USB messages
versaloon Enable building support for the Versallon-lInk JTAG

sdcc

boehm-gc Enable Hans Boehm's garbage collector dev-libs/boehm-gc
device-lib Enable built of devices libraries
ds390 Add support for Dallas DS390
ds400 Add support for Dallas DS400
gbz80 Add support for Gameboy gbz80
hc08 Add support for Freescale/Motorola HC08 based
mcs51 Add support for Intel mcs51
non-free Enable non-free runtime library parts
packihx Enable Intel HEX files pack utility
pic14 Add support for Microchip 14 bits PICs
pic16 Add support for Microchip 16 bits PICs
r2k Add support for Rabbit 2000
r3ka Add support for Rabbit 3000A
s08 Add support for Freescale/Motorola S08
sdbinutils Enable SDCC library archive utilities sdar, sdranlib, sdnm
sdcdb Enable SDCC source level debugger
sdcpp Enable SDCC preprocessor based on GCC cpp
stm8 Add support for STMicroelectronics STM8
tlcs90 Add support for TLCS-90
ucsim Enable software simulator for microcontrollers
z180 Add support for Zilog Z180
z80 Add support for Zilog Z80

urjtag

ftd2xx Enable support for USB FTDI chips via dev-embedded/libftd2xx
ftdi Enable support for USB FTDI chips via dev-embedded/libftdi

dev-games

aseprite

memleak Enable memory-leaks detector (only for developers)
static Link against static version of C and C++ runtimes

cegui

devil Build the DevIL based ImageCodec module
freeimage Build the FreeImage based ImageCodec module
irrlicht Enable the Irrlicht renderer
ogre Enable the OGRE renderer
tinyxml Enable the Tiny XML parser module
xerces-c Enable the Xerces-C++ XML parser module
zip Enable the Minizip resource provider

crystalspace

3ds Enables support for .3DS files in CrystalSpace
bullet include support for Bullet library
cal3d include support for skeleton animation
cegui include support for Crazy Eddie GUI
cg NVIDIA toolkit plugin
ode include support for Open Dynamics Engine

guichan

allegro Build the Allegro frontend

mygui

linguas_ru Install some additional russian docs if 'doc' useflag enabled
ogre Use the ogre render subsystem. (cannot combine with opengl)
opengl Use the opengl render subsystem. (cannot combine with ogre)
plugins Build MyGUI plugins
samples Install MyGUI demos (needs ogre USE flag)
tools Build the tools for development

ode

double-precision more precise calculations at the expense of speed
gyroscopic enable gyroscopic term (may cause instability)

ogre

boost enable boost support
cg NVIDIA toolkit plugin
double-precision more precise calculations at the expense of speed
freeimage support images via freeimage
gl3plus Build OpenGL 3+ RenderSystem (EXPERIMENTAL)
gles2 build OpenGL ES 2.x RenderSystem
gles3 Enable OpenGL ES 3.x Features
ois pull in Object-oriented Input System library for samples
poco when USE=threads, use poco for threading
tbb when USE=threads, use tbb for threading
tools build+install helper tools
zip support zip archives

openscenegraph

asio Enable support for dev-cpp/asio library
fox Build examples using x11-libs/fox library
gdal Enable support for sci-libs/gdal library
openinventor Build OpenInventor plugin
osgapps Build osg applications
xrandr Enable support for the X xrandr extension

physfs

grp Enable Build Engine GRP archive support
hog Enable Descent I/II HOG archive support
mvl Enable Descent I/II MVL archive support
qpak Enable Quake I/II QPAK archive support
wad Enable Doom WAD archive support
zip Enable ZIP archive support

simgear

subversion Enables terrasync scenery downloader

dev-haskell

abstract-deque

usecas Enable the reference implementation to use hardware compare-and-swap.

aeson

developer Operate in developer mode.'

aeson-pretty

lib-only don't build 'aeson-pretty' executable.

ansi-terminal

example Build the example application.

ansi-wl-pprint

example Build the example application.

authenticate

network-uri Get Network.URI from the network-uri package

biosff

fclip Build the fclip executable.
flower Build the flower executable.
frecover Build the frecover executable.

c2hs

regression run regression tests

cabal-install

network-uri Get Network.URI from the network-uri package.
noprefs Ignore 'preferred-versions' file from hackage's tarball.

certificate

executable Build the executable

cgi

extensible-exceptions-in-base Required to be enabled for >=dev-lang/ghc-7.
network-uri Get Network.URI from the network-uri package.

chell

color-output use colors in program output

citeproc-hs

bibutils use Chris Putnam's app-text/bibutils
embed_data_files Embed locale files into the library (needed for windows packaging)
hexpat use dev-haskell/hexpat instead of dev-haskell/xml for XML parsing
network use dev-haskell/network and dev-haskell/http to retrieve CSL file from URIs
small_base Choose the new smaller, split-up base package.
unicode_collation Use Haskell bindings to the dev-libs/icu

cmdargs

quotation Build quote module
testprog Build the test program

comonad

containers You can disable the use of the `containers` package using `-f-containers`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
contravariant You can disable the use of the `contravariant` package using `-f-contravariant`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Contravariant`
distributive You can disable the use of the `distributive` package using `-f-distributive`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Distributive`
test-doctests Run the doctests test suite

conduit

nohandles experimental code to use raw system calls in place of handles. Not recommended for general use

configfile

buildtests Build the executable to run unit tests.

contravariant

semigroups You can disable the use of the `semigroups` package using `-f-semigroups`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
statevar You can disable the use of the `StateVar` package using `-f-StateVar`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
tagged You can disable the use of the `tagged` package on older versons of GHC using `-f-tagged`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

cpu

executable build 'cpuid' tool

crypto-api

all_cpolys Build all the CMAC polynomes up to 10000 bits instead of just the usual ones

crypto-conduit

conduit11 Use conduit >= 1.1.

crypto-numbers

integer-gmp use integer-gmp library

crypto-pubkey

benchmark Build benchmarks.

cryptohash

cryptoapi Defines crypto-api instances

dav

network-uri Get Network.URI from the network-uri package.

distributive

lib-werror Compile with the ghc -Werror option

encoding

systemencoding Provide the getSystemEncoding action to query the locale.

entropy

halvm Build for the HaLVM.

filestore

maxcount Make use of a recent (>= 2.3.0) Darcs feature which vastly improves the performance of 'latest'. You should disable this flag if you plan to use gitit with an older version of Darcs, or 'latest' will raise an error.

glib

closure_signals Use the the GClosure-based signals implementation.

glut

usenativewindowslibraries When compiling under Windows, use the native libraries instead of e.g. the ones coming with Cygwin.

gtk

fmode-binary Set the default file translation mode for file I/O operations to _O_BINARY. Some GTK libraries open image files without specifing binary mode. If you have trouble loading gtk in ghci, then it may help to turn this option off.
gio Depend on GIO package, thereby enabling certain features.

gtk2hs-buildtools

closuresignals Use the the GClosure-based signals implementation.

happstack-server

network-uri Get Network.URI from the network-uri package
template_haskell Description: Template Haskell is available on this system

hashed-storage

diff Provide the Storage.Hashed.Diff module.
hpc Compile with the profiling ghc flag -fhpc.

hashtables

bounds-checking if on, use bounds-checking array accesses
portable if on, use only pure Haskell code and no GHC extensions.
unsafe-tricks turn on unsafe GHC tricks

haskeline

legacy-encoding Use legacy iconv encoding for POSIX. This is only intended for testing.
libiconv Explicitly link against the libiconv library.
terminfo Use the terminfo package for POSIX consoles.

hdbc-odbc

buildstresstest Build stress test

highlighting-kate

executable Build the Highlight executable.
pcre-light Use the pcre-light library instead of regex-pcre-builtin.

hlint

gpl Use GPL libraries, specifically hscolour.

hs3

network-uri Get Network.URI from the network-uri package.

hslogger

buildtests Build the executable to run unit tests.

hslua

apicheck Compile Lua with -DLUA_USE_APICHECK..
system-lua Use the system-wide lua instead of the bundled copy.

hsopenssl

fast-bignum Enable fast moving of bignums between OpenSSL and GMP (GHC Only)

hstringtemplate

quasi-quotation Build module providing a quasi-quoter
syb-with-class Generic instances for TOSElem

http

conduit10 Use version 1.0.x or below of the conduit package (for the test suite).
network-uri Get Network.URI from the network-uri package.

http-client

network-uri Get Network.URI from the network-uri package.

httpd-shed

buildexamples Build example executables.
network-uri Get Network.URI from the network-uri package.

hxt

network-uri Get Network.URI from the network-uri package.

ieee754

big_endian Build for a big endian machine. Beware that only little endian machines have been tested.

json

generic Add support for generic encoder (dev-haskell/syb)
mapdict Encode Haskell maps as JSON dicts
parsec Add support for parsing with Parsec
pretty Add support for using pretty printing combinators

lens

benchmark-uniplate Enable benchmarking against Neil Mitchell's uniplate library for comparative performance analysis. Defaults to being turned off to avoid the extra dependency.
dump-splices Build and run the doctests test-suite.
inlining Generate inline pragmas when using template-haskell. This defaults to enabled, but you can to shut it off to benchmark the relative performance impact, or as last ditch effort to address compile errors resulting from the myriad versions of template-haskell that all purport to be 2.8.
j Attempt a parallel build with GHC 7.8.
lib-werror Turn on ghc-options: -Werror
old-inline-pragmas Some 7.6.1-rc1 users report their TH still uses old style inline pragmas. This lets them turn on inlining.
safe Disallow unsafeCoerce
test-doctests Build and run the doctests test-suite.
test-hlint You can disable the hlint test suite with -f-test-hlint
test-hunit You can disable the hunit test suite with -f-test-hunit
test-properties Build the properties test if we're building tests
trustworthy Assert that we are trustworthy when we can

lifted-async

monad-control-1 Use moand-control == 1.*

monad-control

instancest If enabled this package will export MonadBaseControl instances for the lazy and strict ST monad. If disabled these instances are only exported when base >= 4.4. If enabled it is required that the transformer-base package exports MonadBase instances for ST. It will do this by default.

monad-logger

template_haskell Enable Template Haskell support.

monad-par

chaselev Use Chase-Lev Deques for higher-perf work-stealing.

nats

hashable You can disable the use of the `hashable` package using USE=-hashable. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If set we will not supply an instance of `Hashable`.

pandoc-citeproc

bibutils use Chris Putnam's app-text/bibutils
embed_data_files Embed locale files into the library (needed for windows packaging)
hexpat use dev-haskell/hexpat instead of dev-haskell/xml for XML parsing
network use dev-haskell/network and dev-haskell/http to retrieve CSL file from URIs
small_base Choose the new smaller, split-up base package.
test_citeproc Build the test-citeproc program
unicode_collation Use Haskell bindings to the dev-libs/icu

persistent

nooverlap Use OverlappingInstances only for String. Only developers should use this.

persistent-sqlite

build-sanity-exe Build a sanity check test executable.
systemlib Use the system-wide sqlite library.

quickcheck

template_haskell Enable additional test modules requiring Template Haskell support.

recaptcha

network-uri Get Network.URI from the network-uri package.

reflection

th Enable template haskell.

regex-compat-tdfa

newbase Use base-4.0 or newer.
splitbase Use the new smaller, split-up base package.

rfc5051

mkunicodedata build codes generator itself

sandi

with-conduit Build with conduit

scientific

bytestring-builder Provide the Data.ByteString.Builder.Scientific module (requires bytestring >= 0.10).

semigroupoids

comonad You can disable the use of the `comonad` package using `-f-comonad`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Comonad`
containers You can disable the use of the `containers` package using `-f-containers`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
contravariant You can disable the use of the `contravariant` package using `-f-contravariant`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Contravariant`
distributive You can disable the use of the `distributive` package using `-f-distributive`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Distributive`

semigroups

bytestring You can disable the use of the `bytestring` package using USE=-bytestring. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
containers You can disable the use of the `containers` package using USE=-containers. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
deepseq You can disable the use of the `deepseq` package using `-f-deepseq`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
hashable You can disable the use of the `hashable` package using USE=-hashable. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If set we will not supply an instance of `Hashable`.
text You can disable the use of the `text` package using USE=-text. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
unordered-containers You can disable the use of the `unordered-containers` package using USE=-unordered-containers. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

sendfile

portable Explicitly enable portable sendfile support (implemented in Haskell)

sha

exe Build a sha1 and a sha384 executable similar to 'md5sum'.

shakespeare

test_coffee Render tests through coffeescript render function.
test_export Test export.
test_roy Render tests through roy render function.

shakespeare-js

test_coffee Test coffee.
test_export Test export.
test_roy Test roy.

simple-sendfile

allow-bsd Allow use of BSD sendfile (disable on GNU/kFreeBSD)

skein

big-endian When manually selecting the endianness, use big-endian (default is little-endian).
force-endianness Use a manually selected endian when compiling (see flag 'big-endian').
reference Use the reference implementation instead of the optimized one.

snap-core

portable No non-haskell unportable code.

snap-server

openssl enable https support using dev-haskell/hsopenssl
portable no non-haskell unportable code.

tagsoup

download Build with Download module.
testprog Build the test program.

tasty

colors Enable colorful output

tasty-quickcheck

old-quickcheck Use Quick-Check < 2.7.

texmath

executable Compile test executable.
network-uri Get Network.URI from the network-uri package.

text

developer operate in developer mode

tls

compat Accept SSLv2 compatible handshake

transformers-base

orphaninstances Build instances for orphan datatypes.

transformers-compat

three Use transformers-0.3

unix-compat

old-time build against old-time package

vector

boundschecks Enable bounds checking
internalchecks Enable internal consistency checks at the cost of a significant performance penalty
unsafechecks Enable bounds checking in unsafe operations at the cost of a significant performance penalty

vector-algorithms

bench Build a benchmarking program.
boundschecks Enable bounds checking.
internalchecks Enable internal consistency checks at the cost of a significant performance penalty.
properties Enable quickcheck tests.
unsafechecks Enable bounds checking in unsafe operations at the cost of a significant performance penalty.

void

safe dissable effective but unsafe coersions

wai-app-static

print print debug info.

warp

allow-sendfilefd Allow use of sendfileFd (not available on GNU/kFreeBSD).
warp-debug Add additional debuging information

x11

screensaver whether to build XScreenSaver.

x509-store

executable Build the executable

xss-sanitize

network-uri Get Network.URI from the network-uri package.

yaml

no-exe don't install the yaml2json executable
system-libyaml Use system libyaml instead on generic one

yesod-auth

network-uri Get Network.URI from the network-uri package

yesod-form

network-uri Get Network.URI from the network-uri package

zip-archive

executable Build the Zip executable.

dev-java

ant

antlr Enable ANTLR Ant tasks
bcel Enable bcel (bytecode manipulation) Ant tasks
commonslogging Enable commons-logging Ant tasks
commonsnet Enable commons-net Ant tasks
jai Enable JAI (Java Imaging) Ant task
javamail Enable JavaMail Ant task
jdepend Enable Jdepend Ant tasks
jmf Enable JMF (Java Media Framework) Ant tasks
jsch Disable Jsch (ssh, scp and related) Ant tasks
log4j Enable Apache log4j Ant tasks
oro Enable Apache Oro Ant tasks
regexp Enable Apache Regexp Ant tasks
resolver Enable Apache Resolver Ant tasks
testutil Enable optional test util classes

antlr

gunit gUnit is a "Unit Test" framework for ANTLR grammars
script Install a script to run antlr

bcel

findbugs Include performance patch for findbugs package.

commons-collections

test-framework Install the test framework

commons-logging

avalon-framework Add optional support for avalon-framework
avalon-logkit Add optional support for avalon-logkit
log4j Add optional support for log4j
servletapi Add optional support for servletapi

commons-modeler

commons-digester Add support for the commons-digester based Mbeans Descriptor source

ecj-gcj

native Build a native binary along with the jar. Provides faster execution time, but needs about 1G memory and some patience to compile.

eclipse-ecj

ant Support using ecj in Ant builds via dev-java/ant-eclipse-ecj

emma

launcher Install /usr/bin/emma. Collides with sci-biology/emboss.

gjdoc

xmldoclet Also build support for the xml doclet that generates output in xml instead of the traditional html javadoc.

gnu-classpath

alsa Build with ALSA javax.sound.midi provider
dssi Build with DSSI javax.sound.midi provider
gconf Build with GConf preferences backend
gjdoc Build GJDoc, a documentation generator
gmp Build with GMP backend for java.math.BigInteger
gstreamer Build with GStreamer javax.sound.sampler provider
gtk Build with Gtk+ AWT peers
qt4 Build with Qt4 AWT peers
xml Build with native XML backend

ibm-jdk-bin

javacomm Enable Java Communications API support

icedtea

X Make X buildtime-only depenency.
alsa Make alsa buildtime-only dependency.
cacao Build CACAO virtual machine on platforms supporting HotSpot. (experimental)
cups Make CUPS build-only dependency.
infinality Enable better font rendering using fontconfig.
jamvm Use the JamVM virtual machine rather than HotSpot.
jbootstrap If possible, recompile the final IcedTea executables with itself.
nsplugin Enable browser plugin (NPPlugin), requires also the webstart flag to be enabled.
nss Enable NSS security provider support.
pax_kernel For building when running a PaX enabled kernel.
smartcard Build the PCSC driver against pcsc-lite
sunec Build the SunEC provider against system NSS
systemtap Enable SystemTap probes in HotSpot.
webstart Enable Web Start support (via NetX).
zero Enable Zero assembler port (usually for non-HotSpot architectures)

icedtea-bin

webstart Provide javaws command through symlink to icedtea-web

icedtea-web

icedtea7 Build icedtea-7 support in addition to icedtea-6 support. Requires icedtea{-bin}-7
javascript Enable support for using proxy auto config (PAC) files.
nsplugin Enable the browser plugin (NPPlugin).
tagsoup Depend on dev-java/tagsoup which allows parsing malformed .jnlp files

itext

rtf Build and provide libraries for rich text format
rups Build and provide GUI for Reading/Updating PDF Syntax

jcs

admin Enable JCS Admin servlets

jdbc-jaybird

jni Build/Install JDBC Type 2 native components

jdbc-mysql

c3p0 Enable c3p0 support
log4j Enable log4 support

jdbc-oracle-bin

dms Enable support for the Oracle Dynamic Monitoring Service
ons Enable support for the Oracle Notification Services (ONS) deamon

jfreechart

servlet Build a servlet using the servlet API.

jfreesvg

debug Enable debugging during compilation.

jna

awt Enables support for Java AWT
nio-buffers Enables support for NIO buffers

jython

readline Use GNU readline instead of jline
servletapi Add optional support for servlet-api

log4j

javamail Build the SMTPAppender
jms Build the JMSAppender
jmx Build org.apace.log4j.jmx

logback

tomcat Builds Apache Tomcat support

lucene

contrib Include extra functionality from contrib/

miglayout

swt Add support for the SWT toolkit.

netbeans-nb

keychain Automatically starts keychain on netbeans start and loads specified keys so Netbeans can use them.

oracle-jdk-bin

derby Enable Installation of Bundled Derby (Java DB)
jce Enable Java Cryptographic Extension Unlimited Strength Policy files
pax_kernel Use paxctl to mark the JVM binaries.
source Install JVM and JavaFX sources.

oracle-jre-bin

jce Enable Java Cryptographic Extension Unlimited Strength Policy files
pax_kernel Use paxctl to mark the JVM binaries.

proguard

ant Ant task for using ProGuard in build.xml scripts
j2me Adds support for J2ME Wireless Toolkit

rxtx

lfd Installs and uses LockFileServer daemon (lfd)

sbt

binary Install from (Gentoo-compiled) binary instead of building from sources. Set this when you run out of memory during build.

spymemcached

spring Build support for the spring framework

sun-jdk

derby Enable Installation of Bundled Derby (Java DB)
jce Enable Java Cryptographic Extension Unlimited Strength Policy files
pax_kernel Use paxctl to mark the JVM binaries.

sun-jre-bin

jce Enable Java Cryptographic Extension Unlimited Strength Policy files
pax_kernel Use paxctl to mark the JVM binaries.

swt

webkit Embedded browser support via net-libs/webkit-gtk:2, replacing former xulrunner-based browser.

dev-lang

bas

lr0 Use the LR0 parser instead of the recursive descending parser

erlang

compat-ethread Enable compatibility with pre-pentium 4 CPUs in the ethread library.
halfword Enable halfword emulator
hipe HIgh Performance Erlang extension
kpoll Enable kernel polling support
sctp Support for Stream Control Transmission Protocol

fpc

ide Build and install the Free Pascal Compiler IDE

gdl

eigen Build matrix manipulation with dev-cpp/eigen
grib Add support for the meteorological GRIB format with sci-libs/grib_api
gshhs Add support for projection adn continent maps with sci-geosciences/gshhs-data
hdf Add support for the Hierarchical Data Format v.4
proj Add support for sci-libs/proj (geographic projections)
udunits Add support for manipulating units of physical quantities

ghc

binary Install the binary version directly, rather than using it to build the source version.
ghcbootstrap Bootstrap from an existing GHC installation.
ghcmakebinary Build with less runtime depends (bundle libffi for building bootstrap binaries).
llvm Enable llvm code generator for ghc (-fllvm).

gnat-gcc

lto Add support for link-time optimizations (unsupported, use at your own risk).

icc

eclipse Install the dev-util/eclipse-sdk plugins

icon

iplsrc install the icon programming library source

idb

eclipse Install the dev-util/eclipse-sdk plugins

io

clutter Build add-on for media-libs/clutter
editline Build add-on for dev-libs/libedit
google Build the google search add-on
gui Build the Flux GUI add-on
http Build http client add-on
image Build add-on for images support (jpeg, png, tiff)
libxml2 Build add-on for dev-libs/libxml2
md5sum Build md5sum add-on
sha1 Build sha1 add-on
twitter Build twitter add-on

lazarus

minimal Don't build extra packages from the bigide component

logtalk

fop Support for generating pdf documentation using fop
gnupl Support GNU Prolog back-end compiler
qupl Support Qu-Prolog back-end compiler
swipl Support SWI-Prolog back-end compiler
xsbpl Support XSB back-end compiler
xslt Support for generating html documentation using xslt
yappl Support YAP back-end compiler

lua

deprecated make deprecated data structures/routines available

luajit

lua52compat Enable some upwards-compatible features from Lua 5.2 that are unlikely to break existing code.

mercury

erlang Support Mercury Erlang grade

mlton

binary install a binary version (need to do this once to bootstrap, until smlnj is supported)

mono

pax_kernel Enable if the user plans to run the package under a pax enabled hardened kernel
xen Make mono generate code that is considerably faster on xen VMs but slightly slower on for normal systems.

nqp

moar Build the MoarVM backend (experimental/broken)
parrot Build the parrot backend (default)

path64

assembler Build PathAS
debugger Build PathDB
native Use EKOPath/Path64 for bootstraping
valgrind Use dev-util/valgrind for memory debbuging

perl

ithreads Enable Perl threads, has some compatibility problems

php

cli Enable CLI SAPI
embed Enable embed SAPI
enchant Add supports Enchant spelling library.
fileinfo Add fileinfo extension support
filter Add filter extension support
fpm Enable the FastCGI Process Manager SAPI
gd Adds support for gd (bundled with PHP)
hash Enable the hash extension
intl Enables the intl extension for extended internalization support
json Enable JSON support
ldap-sasl Add SASL support for the PHP LDAP extension
libmysqlclient Use libmyslclient driver for mysql, mysqli, PDO_Mysql (not recommended)
mysqlnd Use native driver for mysql, mysqli, PDO_Mysql
opcache Enables built-in opcode cache, replacing pecl-apc et.al
pdo Enable the bundled PDO extensions
phar Enables the phar extension to provide phar archive support
vpx Enable webp suppoprt for GD
xmlreader Enable XMLReader support
xmlwriter Enable XMLWriter support
xslt Enable the XSL extension
zip Enable ZIP file support

polyml

portable Build the portable interpreter version of Poly/ML instead of native.

python

threads Enable threading support. (DON'T DISABLE THIS UNLESS YOU KNOW WHAT YOU'RE DOING)
wide-unicode Enable wide Unicode implementation which uses 4-byte Unicode characters. Switching of this USE flag changes ABI of Python and requires reinstallation of many Python modules. (DON'T DISABLE THIS UNLESS YOU KNOW WHAT YOU'RE DOING)
wininst Install Windows executables required to create an executable installer for MS Windows.

qu-prolog

pedro Pedro subscription/notification communications system

rakudo

moar Build the MoarVM backend (experimental)
parrot Build the parrot backend (default)

rubinius

llvm Build with llvm. Currently the package only builds against old versions of llvm.

ruby

jemalloc Use dev-libs/jemalloc for memory allocation.
rdoc Install dev-ruby/rdoc after installing Ruby.
readline Use the sys-libs/readline library to provide the readline extension, used for instance by the irb tool. This flag is meaningful only if the libedit USE flag is disabled. If neither libedit nor readline USE flags are enabled, the readline extension will not be built (and irb will lose line editing functionality).
rubytests Install ruby tests that can only be run after ruby is installed
yaml Use the dev-libs/libyaml library to build the psych extension, available since Ruby 1.9.2_rc2, in alternative to the bundled syck-based parser.

rust

clang Use sys-devel/clang for building
libcxx Use sys-libs/libcxx as standard library when building with sys-devel/clang
system-llvm Use system sys-devel/llvm in place of the bundled one

scala

binary Install from (Gentoo-compiled) binary instead of building from sources. Set this when you run out of memory during build.

spidermonkey

debug Enable assertions to allow for easier debugging of programs that link to spidermonkey -- note this will often crash software on regular end-user systems
system-icu Use the system-wide dev-libs/icu instead of bundled -- note, only takes effect when icu flag is enabled
threadsafe Build a threadsafe version of spidermonkey

swi-prolog

archive Use libarchive for extension packs

swig

ccache build ccache-swig(a fast compiler cache)

vala

vapigen Enable vala's library binding generator

yap

R Enable support for connecting R to Prolog

dev-libs

DirectFB

bmp build BMP image provider
divine enable DiVine
drmkms build with DRM/KMS support
dynload enable dynload support
egl build with EGL support
fusiondale enable FusionDale
fusionsound enable FusionSound
gles2 build gles2 gfxdriver
imlib2 build Imlib2 image provider
input_hub provides an asynchronous interface to the input devices available and those being added/removed
mpeg2 build MPEG2 image provider
mpeg3 build Libmpeg3 video provider
multicore enable multicore support
pnm build PNM (PBM/PGM/PPM) image provider
sawman enable SaWMan (window manager and application manager)
swfdec build Swfdec (Flash decoder) video provider
tremor build Ogg/Vorbis music provider using Tremor
webp build WebP image provider

STLport

boost Enable the usage of dev-libs/boost

ace

ciao Include Component Intergraced Ace ORB into the build of ace
tao Include the ACE ORB (CORBA stuff) (called tao) into the build of ace

antlr-c

debugger Compiles debug info into the library

apr

older-kernels-compatibility Enable binary compatibility with older kernels
urandom Use /dev/urandom instead of /dev/random

apr-util

nss Install apr_crypto_nss module
openssl Install apr_crypto_openssl module

bitset

jemalloc Use dev-libs/jemalloc for allocations
tcmalloc Use tcmalloc from dev-util/google-perftools for allocations

blitz

boost Enable usage of boost::serialization

boost

context Build and install the Boost.Context library and all other Boostlibraries that depends on it
debug Build and install only the debug version of the Boost libraries. Only enable this flag if you're developing against boost.
doc Install the full API documentation documentation. This takes over 200MB of extra disk space.
nls Build libboost_locale. This library requires compatible C library interfaces, which might not be provided by uClibc or other embedded libraries.
threads Build multi-thread-compatible libraries instead of single-threaded only.
tools Build and install the boost tools (bcp, quickbook, inspect, wave)

c-blosc

lz4 Enable lz4 compression
snappy Enable snappy compression

check

subunit Enable support for the subunit unit test protocol

cyberjack

fox Enable installation of x11-libs/fox based fxcyberjack program

cyrus-sasl

authdaemond Add Courier-IMAP authdaemond unix socket support (net-mail/courier-imap, mail-mta/courier)
ldapdb Enable ldapdb plugin
openldap Add ldap support for saslauthd
sample Enable sample client and server
srp Enable SRP authentication
urandom Use /dev/urandom instead of /dev/random

dbus-c++

ecore Use Ecore integration
glib Use glib integration

e_dbus

bluetooth Enable interfacing with net-wireless/bluez DBus API.
ofono Enable interfacing with net-misc/ofono DBus API.
test-binaries Enable building of test binaries for enabled features

ecore

ares Enables support for asynchronous DNS using the net-dns/c-ares library
evas Provides easy to use canvas by gluing media-libs/evas and various input/output systems.
gles Add gles support to the ecore-evas-wayland module
glib Enable dev-libs/glib eventloop support
inotify Enable support for inotify
tslib Build with tslib support for touchscreen devices.
wayland Add support for dev-libs/wayland
xprint Enable X11 Xprint support

eeze

utilities Install some test utilities for mount/umount support in eeze

efl

bmp Enable WBMP image loader.
drm Enable DRM engine.
eet Enable Eet image loader.
egl Enable EGL rendering.
fribidi Enable bidirectional text support.
gles Enable the OpenGL ES GL implementation.
glib Enable dev-libs/glib support.
harfbuzz Enable complex text shaping and layout support.
ibus Enable Intelligent Input Bus.
ico Enable Ico image loader.
oldlua USE dev-lang/lua instead of dev-lang/luajit
physics Enable Bullet physics effects and support.
pixman Enable PixMan for software rendering.
ppm Enable PMAPS image loader.
psd Enable PSD image loader.
scim Enable Smart Common Input Method.
tga Enable Tga image loader.
tslib Enable x11-libs/tslib for touchscreen events.
v4l2 Enable Video4Linux2 support.
valgrind Enable usage of dev-util/valgrind in debug
webp Enable WebP image loader.
xim Enable X Input Method.

eina

default-mempool By default use system's allocator (pass-through) instead of custom choice for Eina's own data structures.
mempool-buddy Compile "buddy" memory pool allocation.
mempool-chained-pool Compile "chained-pool" memory pool allocation.
mempool-fixed-bitmap Compile "fixed-bitmap" memory pool allocation.
mempool-one-big Compile "one-big" memory pool allocation.
mempool-pass-through Compile "pass-through" (system's malloc) memory pool allocation.
valgrind Compile in valgrind hints for smoother integration.

elfutils

lzma Support automatic decompression of LZMA-compressed files and kernel images
threads Build the libraries with thread safe support
utils Install command-line utilities (all the eu-* programs)

fampp2

stlport Include support for dev-libs/STLport

fcgi

html Install HTML documentation

ferrisloki

stlport Include support for dev-libs/STLport

folks

telepathy Load contacts from the Telepathy framework
tracker Load contacts from app-misc/tracker index
utils Build the folks-inspect utility
zeitgeist Add support for Zeitgeist event tracking system

fstrm

utils Build fstrm utility programs

gecode

gist Enable Gist, the Gecode Interactive Search Tool

gf2x

bindist Disable automatic fine-tuning to local processor features like pclmul or sse2.

glib

dbus Enable dependencies required by glib libraries using dbus service to manage settings saving
mime Pull in shared MIME database that many glib-based applications require at runtime to detect or open files. Warning: do not disable this flag unless installing on a headless server.
systemtap Build support for profiling and tracing using dev-util/systemtap
utils Install gtester-report utility to generate test report files for your software.

gmp

pgo after building gmp, run some tests against to produce faster libraries -- this option will double the compile time

gobject-introspection

doctool Install g-ir-doc-tool for generating documentation from introspected data

intel-common

compiler Install the libraries needed for the icc and ifort compilers

jemalloc

stats Enable statistics calculation/reporting

keybinder

introspection Use dev-libs/gobject-introspection for introspection

leveldb

snappy support the snappy compression library

libRocket

samples Build samples

libbase58

tools Build command line base58 tool

libburn

cdio Enable EXPERIMENTAL use of libcdio as system adapter
track-src-odirect Read track input with O_DIRECT (see man 2 open), this may deliver a better write performance in some situations

libcdio

minimal Only build the libcdio library and little more, just to be used to link against from multimedia players. With this USE flag enabled, none of the command-line utilities are built, nor is the CDDA library.

libcec

cubox Enable support for enable support for the TDA995x
exynos Enable support for Exynos chipsets
raspberry-pi Enable support for the Raspberry Pi
xrandr Enable detection of active HDMI using xrandr extensions

libcgroup

daemon Install the configuration tools and init/config files.
tools Install the cgroup rules processing daemon and init/config files.

libclsync

extra-debug Enable extra debugging. This will hurt performance badly. Be ready for tons of output.
extra-hardened Enable extra security checks. This may hurt performance.

libdbusmenu

gtk Enable support for GTK+2
gtk3 Enable support for GTK+3
introspection Use dev-libs/gobject-introspection for introspection

libdivecomputer

tools Install tools that can be used to test the library.

libdynd

cuda Enable NVIDIA CUDA toolkit support

libevent

debug Support runtime debug mode and malloc hooks (for programmers)

libffi

pax_kernel Use PaX emulated trampolines, for we can't use PROT_EXEC

libflatarray

cuda Enables plugins for NVIDIA GPUs (e.g. CUDAAllocator)

libgit2

gssapi Enable GSSAPI support for SPNEGO auth
ssh Enable SSH transport support
trace Enable tracing support

libgit2-glib

ssh Enable SSH transport support

libgpg-error

common-lisp Install common-lisp files

libgweather

glade Installs catalog files for dev-util/glade

libindicate

introspection Use dev-libs/gobject-introspection for introspection

libisoburn

cdio Enable EXPERIMENTAL use of libcdio as system adapter
external-filters Allow the use of external processes as file content filters (Note: this is a potential security risk)
external-filters-setuid Also allow the use of external setuid processes as file content filters (Note: this is a potential security risk)
frontend-optional Use dev-tcltk/bwidget which is not strictly required for the frontend
launch-frontend Enable the tcl gui for xorriso
launch-frontend-setuid Enable the tcl gui for xorriso under setuid

libisofs

verbose-debug Enable verbose debug messages

libjit

interpreter Enable the libjit interpreter
long-double Enable the use of long double for jit_nfloat

liblogging

rfc3195 Enables RFC 3195 protocol (aka syslog-reliable) support. If you don't know what this is, you don't need it!
stdlog Enables liblogging's core component (think of it as a the next version of the syslog(3) API).

libmail

apop Enables the APOP authentication method

libmemcached

hsieh Use Hsieh hash algorithm.
libevent Use the libevent event loop interface.
sasl Use sasl auth for communications.

libnfc

pcsc-lite Enable NFC drivers that require pcsc-lite

libnl

doc Install development documentation
python Install experimental dev-lang/python bindings
utils Install command line interface utils

libowfat

diet Compile against dev-libs/dietlibc

libp11

doc Generate and install API documentation for the package.

libpcre

bzip2 Add support for pcregrep command to search within bzip2-compressed files, through sys-libs/zlib.
pcre16 Build 16 bit PCRE library.
pcre32 Build 32 bit PCRE library.
readline Add support for command line editing to pcretest, through sys-libs/readline.
recursion-limit Limit match recursion to 8192; if disabled, the default limit is used, which is the same as the match limit.
zlib Add support for pcregrep command to search within gzip-compressed files, through app-arch/gzip.

libpeas

glade Install the glade catalog
python Build support for loading dev-lang/python plugins

librra

recurrence Enable recurrence support (EXPERIMENTAL)

libsecp256k1

asm Enable x86_64 assembly optimisation
endomorphism Enable endomorphism

libsodium

asm Enables assembly implementations
urandom Use /dev/urandom instead of /dev/random

libsqlora8

orathreads Use Oracle threads

libtermkey

demos Install demos, which pulls in dev-libs/glib

libunique

introspection Use dev-libs/gobject-introspection for introspection

libverto

glib Support event loops using dev-libs/glib
libev Support event loops using dev-libs/libev
libevent Support event loops using dev-libs/libevent
tevent Support event loops using sys-libs/tevent
aspell Adds support for app-text/aspell spell checker
hunspell Adds support for app-text/hunspell spell checker

log4cplus

iconv Use inconv for wchar_t <-> char conversions. See also log4cplus's unicode.txt documentation
working-c-locale Use the C99 locale facilities for wchar_t <-> char conversions. See also log4cplus's unicode.txt documentation
working-locale Use C++'s std::locale for wchar_t <-> char conversions. See also log4cplus's unicode.txt documentation

log4cxx

smtp Offer SMTP support via net-libs/libesmtp

m17n-lib

X Builds the Graphical User Interface API and utilities for the package.
anthy Enable support for app-i18n/anthy input method.
athena Enable the MIT Athena widget set (x11-libs/libXaw)
gd Build API and utilities based on media-libs/gd. This flag is only meaningful if the X USE flag is also enabled.
libotf Use dev-libs/libotf to handle OpenType fonts
libxml2 Use dev-libs/libxml2 to parse XML

nss

cacert Include root certs from CAcert (http://http://www.cacert.org/) and Software in the Public Interest (http://www.spi-inc.org/)
nss-pem Add support for libnsspem
utils Install utilities included with the library

oniguruma

combination-explosion-check enable combination explosion check
crnl-as-line-terminator enable CR+NL as line terminator

opencryptoki

tpm Enable support for Trusted Platform Module (TPM) using app-crypt/trousers

openct

debug Add debug output to the driver library for pcsc-lite.
pcsc-lite Build a driver library for sys-apps/pcsc-lite, providing PC/SC API access to devices supported by OpenCT.
udev Install rules for sys-fs/udev to auto-start openct.

openobex

irda Enable IrDA support

opensc

ctapi Use CT-API for accessing Smartcard hardware.
libtool Use sys-devel/libtool for dynamically loading libraries rather than the host libdl/dlopen helpers.
openct Use dev-libs/openct (and CT-API) for accessing Smartcard hardware.
pcsc-lite Use sys-apps/pcsc-lite (and PC/SC API) for accessing Smartcard hardware.
secure-messaging Enable secure messaging.

openssl

asm Support assembly hand optimized crypto functions (i.e. faster run time)
bindist Disable EC algorithms (as they seem to be patented) -- note: changes the ABI
rfc3779 Enable support for RFC 3779 (X.509 Extensions for IP Addresses and AS Identifiers)
sctp Support for Stream Control Transmission Protocol
tls-heartbeat Enable the Heartbeat Extension in TLS and DTLS

pkcs11-helper

nss Enable NSS crypto engine

ppl

lpsol Build the ppl_lpsol linear programming problem solver

soprano

raptor Enables support for media-libs/raptor RDF parser/serializer.
redland Enables support for the dev-libs/redland storage backend (really slow one).
virtuoso Enables support for dev-db/virtuoso storage backend.

starpu

cuda Enable NVIDIA CUDA toolkit support
gcc-plugin Enable GCC extension plugin (experimental)
opencl Enable OpenCL support

tinyxml

stl Compile with TIXML_USE_STL support

tntnet

server Enable tntnet server daemon

totem-pl-parser

archive Enables support for accessing media files in archives transparently via app-arch/libarchive
quvi Use media-libs/libquvi for parsing video links

ucommon

socks Build with socks proxy support

weston

colord Allow setting color managment
drm Enable drm compositor support
editor Install wayland-editor example application
egl Enable egl acceleration
fbdev Enable fbdev compositor support
gles2 Use GLESv2 cairo instead of full GL
headless Headless backend and a noop renderer, mainly for testing purposes
ivi Enable the IVI shell
launch Install weston-launch utility
rdp Enable Remote Desktop Protocol compositor support
resize-optimization Increase performance, allocate more RAM. Recommended to disable on Raspberry Pi
rpi Raspberry Pi GPU support
screen-sharing Enable screen-sharing through RDP
tablet Enable interface for tablets
unwind Enable libunwind usage for backtraces
view Install wayland-view example application
wayland-compositor Enable Wayland compositor support
xwayland Enable ability support native X11 applications

xapian

brass Enabled brass backend db support
chert Enabled chert backend db support
inmemory Enabled inmemory backend db support

xerces-c

iconv Use iconv (virtual/libiconv) as message loader and transcoder (in general it would be possible to use iconv only as message loader and something else like icu or the native method as transcoder and vice-versa, but this is a less common case and hard to handle)
threads Enable threading support through pthread (or other libraries on AIX, IRIX, HPUX, Solars). Highly recommended

xml-security-c

nss Use dev-libs/nss for certain crypto operations (configureable at runtime)
xalan Enable support for XSLT and XPath parsing by dev-libs/xalan-c

xmlrpc-c

abyss Build the Abyss mini web-server.
libxml2 Use dev-libs/libxml2 to parse XML instead of the internal expat library.
threads Controls whether to build the Abyss web-server with pthreads or fork 'threading'.
tools Build the xmlrpc* tools.

xmlsec

gcrypt Install xmlsec-gcrypt library
gnutls Install xmlsec-gnutls library
nss Install xmlsec-nss library
openssl Install xmlsec-openssl library

xqilla

faxpp Use dev-libs/faxpp instead of Xerces-C for certain tasks
htmltidy Use app-text/htmltidy when parsing HTML

yaz

ziffy Install ziffy, a promiscuous Z39.50 APDU sniffer

dev-lisp

abcl

clisp Build Armed Bear Common Lisp using GNU CLISP
cmucl Build Armed Bear Common Lisp using CMU Common Lisp
jad Enable support for disassembling compiled code using JAD

clisp

hyperspec Use local hyperspec instead of online version
new-clx Build CLISP with support for the NEW-CLX module which is a C binding to the Xorg libraries
pari Build CLISP with support for the PARI Computer Algebra System
svm Build CLISP with support for the Support Vector Machine module

clx

doc Builds documentation

cmucl

source Include source code for CMUCL in installation

ecls

gengc Use generational garbage collection (experimental)
libatomic Use dev-libs/libatomic_ops library
precisegc Use type information during garbage collection (experimental)

gcl

ansi Build a GCL with ANSI support (else build a traditional CLtL1 image)
athena Build xgcl - an interface to x11-libs/libXaw

sbcl

asdf Include support for dev-lisp/asdf in SBCL
ldb Include support for the SBCL low level debugger
pax_kernel Enable if the user plans to run the package under a pax enabled hardened kernel

dev-lua

luarocks

curl Uses net-misc/curl for fetching lua packages instead of net-misc/wget.
openssl Uses dev-libs/openssl for verifying lua packages instead of md5sum.

luvit

bundled-libs Use bundled versions of some libraries.
system-libs Use system version of dev-libs/yajl.

messagepack

luajit Use the lua just-in-time compiler dev-lang/luajit instead of dev-lang/lua

dev-ml

cairo-ocaml

pango Enable support for x11-libs/pango

deriving-ocsigen

type-conv Enable type-conv for the syntax extention.

dose3

parmap Adds multi-core CPU support via dev-ml/parmap.
rpm4 Adds support for handling rpm4 files.
zip Adds support for handling zip files.

js_of_ocaml

deriving Enable dev-ml/deriving support for improving the type safety.
deriving-ocsigen Enable deriving-ocsigen for improving the type safety.

lablgtk

glade Enable libglade bindings compilation.
gnomecanvas Enable libgnomecanvas bindings compilation.
sourceview Enable GtkSourceView support

lwt

react Enables support for dev-ml/react: Functional reactive programming (signals, events, etc.).
text Enables text mode utilities.
toplevel Enables enhanced toplevel.

ocamlnet

cryptokit Enables encryption support via dev-ml/cryptokit
httpd Enables net-httpd web server component
zip Enables netzip support to read/write gzip data using object channels

pgocaml

batteries Enable Batteries support instead of extlib

utop

camlp4 Enables camlp4 support.

uutf

utftrip Builds and install the utftrip executable: Among other things, reads unicode on stdin and rewrites it on stdout.

dev-perl

App-Nopaste

clipboard copying of URLs with -x/--copy
github Github authentication
pastebin pastebin.com support

DBD-mysql

embedded Support embedded server (libmysqld)

DBIx-Class

admin Modules required for the DBIx::Class administrative library
admin_script Modules required for the CLI DBIx::Class interface dbicadmin
deploy Modules required for "deploy" in DBIx::Class::Storage::DBI and "deploymen_statements" in DBIx::Class::Storage::DBI
replicated Modules required for DBIx::Class::Storage::DBI::Replicated

File-HomeDir

xdg Ensure XDG Semantics for returned paths via x11-misc/xdg-user-dirs

GD

animgif Enable animated gif support

Graphics-ColorNames

recommended Install recommended support modules

HTML-Mason

modperl Enable www-apache/mod_perl support

Lab-Measurement

xpression Install the Xpression measurement framework

Log-Dispatch

ithreads Ensure perl is built with threads for Syslog 'lock' feature

Net-OpenSSH

sftp Enable SFTP protocol support.

Net-SSH2

gcrypt Use libgcrypt instead of openssl

PDL

badval Enable bad values support
hdf Enable HDF (version 4) format support
netpbm Enable NETPBM and MPEG support
pdl2 Build pdf2 shell (requires Devel-REPL)
pgplot Enable PGPLOT plotting capabilities
plplot Enable plplot plotting capabilities

Panotools-Script

gui Installs GUIs for some tools

Sysadm-Install

hammer Enable hammer() funtion to run a command in the shell and simulate a user hammering the ENTER key to accept defaults on prompts

dev-php

PEAR-HTTP_Download

minimal Do not include support for PEAR-MIME_Type
postgres Send postgres LOBs without buffering

PEAR-HTTP_Request2

curl Force dev-lang/php to be compiled with curl extension
fileinfo Force dev-lang/php to be compiled with fileinfo extension
ssl Force dev-lang/php to be compiled with ssl extension
zlib Force dev-lang/php to be compiled with zlib extension

PEAR-PHP_Shell

auto-completion Enable tab-completion

ZendFramework

cli Enables the CLI
doc Installs the documentation
examples Installs the examples
minimal Installs the minimal version without Dojo toolkit, tests and demos

pecl-apcu

lock_pthreadmutex Enable pthread mutex locking
lock_pthreadrw Enable pthread read/write locking
lock_semaphore Enable semaphore locks instead of fcntl
lock_spinlock Enable spin locks (EXPERIMENTAL)

pecl-event

extra Add support of the Libevent extra API

pecl-memcached

igbinary Enable support for the igbinary serializer
json Enable support for json serialization

pecl-mysqlnd_qc

memcached Use dev-libs/libmemcached as a storage handler
sqlite Use dev-db/sqlite as a storage handler

pecl-redis

igbinary Enables igbinary serialisation support

smarty-docs

html Install the documentation in HTML format
pdf Install the documentation in PDF format

dev-python

Kivy

camera Install libraries needed to support camera
garden Install garden tool to manage user maintained widgets

PyFoam

extras Enable optional dependencies

PyQt4

X Build bindings for the QtGui module
dbus Build bindings for the QtDBus module
declarative Build bindings for the QtDeclarative module
designer Build bindings for the QtDesigner module and enable the designer plugin
help Build bindings for the QtHelp module
kde Select media-libs/phonon as Phonon variant (needed for KDE)
multimedia Build bindings for the QtMultimedia module
opengl Build bindings for the QtOpenGL module
phonon Build bindings for the phonon module
script Build bindings for the QtScript module
scripttools Build bindings for the QtScriptTools module
sql Build bindings for the QtSql module
svg Build bindings for the QtSvg module
testlib Build bindings for the QtTest module
webkit Build bindings for the QtWebKit module
xmlpatterns Build bindings for the QtXmlPatterns module

PyQt5

dbus Build bindings for the QtDBus module
declarative Build bindings for the QtQml/QtQuick modules and enable the qmlscene plugin
designer Build bindings for the QtDesigner module and enable the designer plugin
gles2 Use GLES 2.0 or later instead of full OpenGL
gui Build bindings for the QtGui module
help Build bindings for the QtHelp module
multimedia Build bindings for the QtMultimedia module
network Build bindings for the QtNetwork module
opengl Build bindings for the QtOpenGL module
positioning Build bindings for the QtPositioning module
printsupport Build bindings for the QtPrintSupport module
sensors Build bindings for the QtSensors module
serialport Build bindings for the QtSerialPort module
sql Build bindings for the QtSql module
svg Build bindings for the QtSvg module
testlib Build bindings for the QtTest module
webchannel Build bindings for the QtWebChannel module
webkit Build bindings for the QtWebKit module
websockets Build bindings for the QtWebSockets module
widgets Build bindings for the QtWidgets module
x11extras Build bindings for the QtX11Extras module
xmlpatterns Build bindings for the QtXmlPatterns module

PyQtMobility

contacts Build bindings for the QtContacts module
feedback Build bindings for the QtFeedback module
gallery Build bindings for the QtGallery module
location Build bindings for the QtLocation module
messaging Build bindings for the QtMessaging module
multimedia Build bindings for the QtMultimediaKit module
organizer Build bindings for the QtOrganizer module
publishsubscribe Build bindings for the QtPublishSubscribe module
sensors Build bindings for the QtSensors module
serviceframework Build bindings for the QtServiceFramework module
systeminfo Build bindings for the QtSystemInfo module
versit Build bindings for the QtVersit module

amqplib

extras Install extra tools to generate initial Python mod from an AMQP XML file

anyvc

bazaar Add support for Bazaar
mercurial Add support for Mercurial

celery

redis Enables redis support
sqs Enables Amazon SQS transport module for celery
yaml Enable support of yaml as a configuration file format
zeromq Enable logging and deployment via ZeroMQ

cgkit

3ds Enable support for importing 3D Studio models

cvxopt

dsdp Use interior point library sci-libs/dsdp
glpk Use GNU Linear Programming Kit sci-mathematics/glpk

dap

server Enable OpenDAP server support

django-extensions

graphviz Create a diagram of your database entity relationships using dev-python/pygraphviz.
s3 Upload your media files to S3.
vcard Export your users email addresses to the vcard format.

django-tastypie

bip An optional serialiser dev-python/biplist
digest Library to aid in implementing HTTP Digest Authentication
lxml An optional serialiser dev-python/lxml
yaml An optional serialiser dev-python/yaml

django-two-factor-auth

yubikey Adds support for Yubikeys via django-otp-yubikey

docutils

glep Install support for GLEPs

falcon

cython Build cython-based python modules

flask-restful

paging Enable resource paging support

geopy

timezone Enables localized date support
yahoo Enables use of YahooPlaceFinder

gmpy

mpir Use sci-libs/mpir as gmp implementation

icalendar

doc Generate examples and other extra documentation

ipython

matplotlib Add support for dev-python/matplotlib
mongodb Enable support for MongoDB via dev-python/pymongo
nbconvert Enable support for converting notebooks to various formats using app-text/pandoc
notebook Install requirements for the web notebook based on www-servers/tornado
octave Enable octave bridge via dev-python/oct2py

kaa-base

tls SSL/TLS support via dev-python/tlslite

kazoo

gevent Enable support for the gevent based handler

kombu

amqplib Enable amqplib support
msgpack Enables MessagePack (de)serializer for Python
sqs Enables Amazon SQS transport module for Kombu

lxml

beautifulsoup3 Enable support for Beautiful Soup 3

markdown

pygments Enable fancy pygments support

matplotlib

excel Pull dev-python/xlwt for the exceltools toolkit
gtk3 Use x11-libs/gtk+:3 instead of x11-libs/gtk+:2
pyside Qt support via dev-python/pyside

mpmath

matplotlib Add support for dev-python/matplotlib

mwlib

server Install the daemons required when using mwlib for generating PDFs on a MediaWiki instance.

mwlib-rl

pdftk Enable support for app-text/pdftk, required to generate TOCs

netaddr

cli Enable netaddr shell with dev-python/ipython

nltk

numpy Use numpy for the saved word tokenizer

numexpr

mkl Enable support for Intel Vector Math Library, part of sci-libs/mkl.

pandas

R Enable support for R via dev-python/rpy
excel Pull a few Python packages for Microsoft Excel i/o
html Enable HTML i/o via dev-python/beautifulsoup

paste

flup enable support for flup (and therefore for various wgsi servers and middleware)
openid enable OpenID support

pillow

webp Enable support for webp image format.

py-amqp

extras Install extra tools to generate initial Python mod from an AMQP XML file

pyhamcrest

numpy Enable optional dependence on dev-python/numpy

pylons

genshi Add optional genshi support
jinja Add optional jinja support

pymongo

mod_wsgi Disable the C extension to work with mod_wsgi.

pyocr

cuneiform Enable support for the app-text/cuneiform OCR engine
tesseract Enable support for the app-text/tesseract OCR engine

pypax

ptpax Enable PT_PAX_FLAGS support.
xtpax Enable XATTR_PAX_FLAGS support.

pyplusplus

indexing Install indexing_suite_v2 to enhance boost python
numpy Generate code for dev-libs/boost-numpy to accelerate arrays

pypy

low-memory Build using PyPy with the engine configured towards low memory footprint. \ This makes it possible to build PyPy using ~3.5G of RAM on amd64 and ~half of that on x86, at the cost of lengthened build time. Please note that you will need an extra ~1G of extra RAM or \ swap since the translation memory (unused at the time) is not freed when the C compiler is spawned.
sandbox Enable sandboxing functionality
shadowstack Use a shadow stack for finding GC roots

pypy-bin

shadowstack Use a shadow stack for finding GC roots

pypy3

low-memory Build using PyPy with the engine configured towards low memory footprint. This makes it possible to build PyPy using ~3.5G of RAM on amd64 and ~half of that on x86, at the cost of lengthened build time. Please note that you will need an extra ~1G of extra RAM or swap since the translation memory (unused at the time) is not freed when the C compiler is spawned.
sandbox Enable sandboxing functionality
shadowstack Use a shadow stack for finding GC roots

pypy3-bin

shadowstack Use a shadow stack for finding GC roots

pyquery

beautifulsoup3 Support BeautifulSoup 3

pyside

X Build QtGui and QtTest modules
declarative Build QtDeclarative module
designer Build QtDesigner and QtUiTools modules
help Build QtHelp module
multimedia Build QtMultimedia module
opengl Build QtOpenGL module
phonon Build phonon module
script Build QtScript module
scripttools Build QtScriptTools module
sql Build QtSql module
svg Build QtSvg module
webkit Build QtWebKit module
xmlpatterns Build QtXmlPatterns module

python-stdnum

vies Enable VIES

pyudev

pygobject Install PyGobject binding
pyqt4 Install PyQt4 binding
pyside Install PySide binding

pyyaml

libyaml enable support for C implementation using libyaml

pyzmq

green Enable gevent compatibility with zeromq

pyzor

gevent Enable support for the gevent based handler
mysql Enables mysql support
pyzord enable support for pyzord
redis Enables redis support

rarfile

compressed Enables the module to support compressed v3 archives by calling the app-arch/unrar.

rdflib

redland enable support for Redland triplestore

restkit

cli Install the restcli command line interface/tool, based on dev-python/ipython

scrapy

boto Add support for Amazon S3 via dev-python/boto
ibl Use Instace Based Learning alrogirithm for automatic extraction

simplecv

shell Enable the iPython SimpleCV shell

spyder

ipython Add support for dev-python/ipython
matplotlib Add support for dev-python/matplotlib
numpy Add support for dev-python/numpy
pep8 Add support for dev-python/pep8
pyflakes Add support for dev-python/pyflakes
pylint Add support for dev-python/pylint
rope Add support for dev-python/rope
scipy Add support for sci-libs/scipy
sphinx Add support for dev-python/sphinx

starcluster

epydoc Enable build of apidocs in html using epydoc

sympy

imaging Add support for dev-python/imaging
ipython Add support for dev-python/ipython
mathml Add support for mathml
pyglet Use dev-python/pyglet for plots and print preview
system-mpmath Use mpmath from portage instead of the bundled one
texmacs Add app-office/texmacs interface
theano Add support for dev-python/theano

tdaemon

coverage Enable code coverage support

translate-toolkit

html Support conversion between po and html files
ical Support conversion between po and ical files
ini Support conversion between po and ini files
subtitles Support conversion between po and sub files

twisted-core

serial include serial port support

vatnumber

vies Enable VIES

ws4py

client Install client modules
server Install server modules

wxpython

doc Install HTML wxWidgets docs and wxpython API reference.
examples Install interactive demo module browser and sample applets.

zsi

twisted add support for dev-python/twisted

dev-qt

assistant

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

designer

declarative Build the qdeclarativeview plugin
exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
phonon Build the phononwidgets plugin
qt3support Build the qt3supportwidgets plugin
webkit Build the qwebview plugin

linguist

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

linguist-tools

qml Enable QML support in lupdate

pixeltool

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qdbusviewer

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qt-creator

android Build plugin for Android devices
autotools Enable autotools project manager plugin
baremetal Build plugin for bare metal devices
bazaar Add support for dev-vcs/bzr version control system
clang Build clang-based code model plugin
clearcase Add support for IBM ClearCase version control system (requires manual installation of ClearCase client)
cmake Enable cmake project manager plugin
fakevim Enable support for vim-like key bindings
ios Build plugin for Apple iOS devices
madde Enable integration with MADDE (Maemo Application Development and Debugging Environment)
mercurial Add support for dev-vcs/mercurial version control system
perforce Add support for Perforce version control system (requires manual installation of Perforce client)
python Enable Python source code editor
qbs Enable QBS project manager plugin
qnx Build plugin for QNX/Blackberry devices
systemd Add support for retrieving application output from journald
valgrind Add support for memory debugging using dev-util/valgrind
winrt Build plugin for WinRT devices

qt-meta

kde Select media-libs/phonon as Phonon variant (needed for KDE)
openvg Enable the QtOpenVG module
qt3support Enable the Qt3Support library for Qt4

qt-mobility

bluetooth Enable Bluetooth support in QtConnectivity and QtSystemInfo modules
connectivity Build the QtConnectivity module
contacts Build the QtContacts module
feedback Build the QtFeedback module
gallery Build the QtGallery module
location Build the QtLocation module
messaging Build the QtMessaging module
multimedia Build the QtMultimediaKit module
networkmanager Enable NetworkManager support in QtBearer and QtSystemInfo modules
organizer Build the QtOrganizer module
publishsubscribe Build the QtPublishSubscribe module
pulseaudio Enable PulseAudio support in QtMultimediaKit module
qml Build QML bindings
sensors Build the QtSensors module
serviceframework Build the QtServiceFramework module
systeminfo Build the QtSystemInfo module
tools Build various useful tools (e.g.: qcrmlgen, servicexmlgen, vsexplorer, ...)
versit Build the QtVersit module

qt3support

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qtbearer

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qtcore

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
glib Enable dev-libs/glib eventloop support
qt3support Enable the Qt3Support libraries for Qt4. Note that this does not mean you can compile pure Qt3 programs with Qt4.

qtdbus

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qtdeclarative

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
gles2 Use GLES 2.0 or later instead of full OpenGL
localstorage Build the LocalStorage import for QtQuick (requires QtSql)
qt3support Enable the Qt3Support libraries for Qt4. Note that this does not mean you can compile pure Qt3 programs with Qt4.
webkit Build the WebView QML component
widgets Enable QtWidgets support
xml Build the XmlListModel import for QtQuick (requires QtXmlPatterns)

qtdemo

dbus Build QtDBus examples and demos
declarative Build QtDeclarative examples and demos
exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
multimedia Build QtMultimedia examples and demos
opengl Build QtOpenGL examples and demos
openvg Build QtOpenVG examples and demos
phonon Build Phonon examples and demos
qt3support Build Qt3Support examples and demos
webkit Build QtWebKit examples and demos
xmlpatterns Build QtXmlPatterns examples and demos

qtgui

egl Use EGL instead of default GLX to manage OpenGL contexts
eglfs Compile EGL Full Screen/Single Surface support
evdev Enable evdev input support
exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
gles2 Use GLES 2.0 or later instead of full OpenGL
glib Enable dev-libs/glib eventloop support
gtkstyle Build a Qt style called GTK+ that mimics the active GTK+ theme
harfbuzz Use media-libs/harfbuzz for text shaping
ibus Build the IBus input method plugin
qt3support Enable the Qt3Support libraries for Qt4. Note that this does not mean you can compile pure Qt3 programs with Qt4.
trace Build the 'trace' graphicssystem engine which allows to record all drawing operations into a trace buffer. The trace can be replayed later with the qttracereplay tool.

qthelp

compat Build the extra compatibility layer required by a few packages, see http://blog.qt.digia.com/blog/2010/06/22/qt-assistant-compat-version-available-as-extra-source-package/
exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qtmultimedia

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
qml Build QML/QtQuick bindings and imports
widgets Build the QtMultimediaWidgets module

qtnetwork

bindist Disable EC support via dev-libs/openssl
connman Enable net-misc/connman-based bearer plugin
networkmanager Enable net-misc/networkmanager-based bearer plugin

qtopengl

egl Use EGL instead of default GLX to manage OpenGL contexts on the desktop
exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
gles2 Use GLES 2.0 or later instead of full OpenGL
qt3support Enable the Qt3Support libraries for Qt4

qtopenvg

exceptions Build with support for exceptions
qt3support Enable the Qt3Support libraries for Qt4

qtphonon

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
qt3support Enable the Qt3Support libraries for Qt4. Note that this does not mean you can compile pure Qt3 programs with Qt4.

qtpositioning

geoclue Use enhanced location information from app-misc/geoclue
qml Build QML bindings

qtprintsupport

gles2 Use GLES 2.0 or later instead of full OpenGL

qtquick1

designer Build plugin for dev-qt/designer
webkit Build the WebView import for QtQuick1 (requires QtWebKit)
xml Build the XmlListModel import for QtQuick1 (requires QtXmlPatterns)

qtquickcontrols

widgets Enable QtWidgets support

qtscript

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
scripttools Build the QtScriptTools module (requires QtWidgets)

qtsensors

qml Build QML bindings

qtsql

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
qt3support Enable the Qt3Support libraries for Qt4

qtsvg

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qttest

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)

qtwayland

egl Use EGL instead of GLX to manage OpenGL contexts
qml Build QML/QtQuick bindings
wayland-compositor Build Qt compositor for wayland

qtwebchannel

qml Build QML/QtQuick bindings and imports

qtwebkit

exceptions Add support for exceptions - like catching them inside the event loop (recommended by upstream)
gstreamer Enable HTML5 audio/video support via media-libs/gstreamer
gstreamer010 Enable HTML5 audio/video support via legacy media-libs/gstreamer:0.10
multimedia Enable HTML5 audio/video support via dev-qt/qtmultimedia
printsupport Enable printing via dev-qt/qtprintsupport
qml Build QML/QtQuick bindings
webp Add support for WebP image format

qtwebsockets

qml Build QML bindings

qtwidgets

gles2 Use GLES 2.0 or later instead of full OpenGL
gtkstyle Build a Qt style called GTK+ that mimics the active GTK+ theme

dev-ruby

barby

cairo Add support for writing images (PNG, PS, EPS and, if supported, PDF and SVG) using dev-ruby/rcairo. Not available on JRuby.
datamatrix Add support for datamatrix using dev-ruby/semacode.
pdf-writer Add support for writing PDFs using dev-ruby/pdf-writer.
png Add support for writing PNG images using dev-ruby/chunky_png.
prawn Add support for writing PDF documents using dev-ruby/prawn.
qrcode Add support for QRCode 2D codes using dev-ruby/rqrcode.
rmagick Add support for writing images (among others PNG, GIF and JPEG) using dev-ruby/rmagick. Not available on JRuby.

facter

dmi Use sys-apps/dmidecode to determine hardware system properties
pciutils Use sys-apps/pciutils to determine hardware system properties
virt Use app-emulation/virt-what for virtual machine detection

faraday_middleware

mashify Include FaradayMiddleware::Mashify
oauth Include FaradayMiddleware::OAuth
parsexml Include FaradayMiddleware::ParseXml
rashify Include FaradayMiddleware::Rashify

maruku

highlight Enable source code highlighting via dev-ruby/syntax

rails

asset-pipeline Also install the default components for the asset pipeline. These are not required but they are activated automatically in new Rails projects by default.

rrdtool-bindings

graph Enable support for graphing functions

rspec-core

highlight Enable source code highlighting via dev-ruby/coderay

ruby-sdl

image Enable media-libs/sdl-image support
mixer Enable media-libs/sdl-mixer support
sge Enable sdl-sge support

rubygems

server Install support for the rubygems server

dev-scheme

bigloo

bglpkg Build bglpkg binary, which can be use to access scmpkg servers (requires web)
calendar Build the embedded library for calendar programming
crypto Build the embedded cryptographic library
debug Enable extra debug codepaths
doc Install Bigloo Manual (HTML docs of Bigloo and r5rs)
emacs Build and install the Bigloo Developement Environment for Emacs (aka bee-mode)
gmp Adds support for dev-libs/gmp (GNU MP library)
java Enable the JVM backend for the Bigloo compiler
mail Mail library for email management (e.g. maildir and imap support)
multimedia Build multimedia library (e.g. for managing images). Needed for dev-scheme/hop
openpgp Build OpenPGP support (requires crypto)
packrat Bigloo port of Tony Garnock-Jones' packrat parser (requires srfi1)
sqlite Use the system-wide dev-db/sqlite
srfi1 Build the srfi1 library: List library
srfi27 Build the srfi27 library: Source of Random Bits (32bit-arch only, requires gmp)
ssl Adds support for SSL connections through dev-libs/openssl
text Library for dealing with text (e.g. BibTeX parser)
threads Enable thread support, it depends on dev-libs/boehm-gc built with threads use flag
web Library for web programming (e.g. XML, CGI parsers). Needed for dev-scheme/hop

chicken

parallel-build Enable testing parallel build mode added in 4.7.3 version. Can still be not working

gauche-gl

cg Enable NVidia Cg binding

gauche-gtk

glgd Enable GL graph draw

guile

debug-freelist Include garbage collector freelist debugging code
debug-malloc Include malloc debugging code
deprecated Enable deprecated features
discouraged (implied by deprecated) enable merely discouraged features
networking Include networking interfaces
regex Include regular expression interfaces

hop

debug Enables building with debug symbols
ssl Enable SSL support for hop
threads Enable thread support for hop, it depends on dev-scheme/bigloo built with threads use flag.

kawa

awt Assume AWT is available
echo2 Enable support for the Echo2 web toolkit with dev-java/echo2
frontend Build "kawa" front-end program using sys-libs/readline
jemacs Build JEmacs
krl Build BRL emulation and KRL
sax Assume SAX2 is available with dev-java/sax
servlets Build support for generating servlets with dev-java/servletapi
swing Assume Swing is available
swt Assume SWT is available with dev-java/swt
xqtests Support XQuery Test Suite

racket

backtrace Support GC backtrace dumps
futures Enable racket/future library for fine-grained hardware parallelism
places Enable racket/place library for share-nothing parallelism and message-passing communication. Compared to futures, places are heavyweight, but they have a simpler performance model.
plot Enable plot libraries
threads Enable support for green threads

scm

arrays Support for arrays, uniform-arrays and uniform-vectors.
bignums Support for large precision integers.
cautious SCM will always check the number of arguments to interpreted closures.
dynamic-linking Be able to load compiled files while running.
engineering-notation Floats to display in engineering notation (exponents always multiples of 3) instead of scientific notation.
gsubr generalized c arguments: for arbitrary (more then 11) arguments to C functions.
inexact Support for floating point numbers.
ioext Commonly available I/O extensions: line I/O, file positioning, file delete and rename, and directory functions.
macro C level support for hygienic and referentially transparent macros (syntax-rules macros).
regex String regular expression matching.
unix Support for: nice, acct, lstat, readlink, symlink, mknod and sync.

dev-tcltk

expect-lite

debug pull in packages needed for runtime interactive debugger

tktreectrl

shellicon shellicon extension

dev-tex

abntex

lyx Install with app-office/lyx layout

circuit_macros

script Install cm2pdf to automatically create a correctly sized PDF from a circuit_macro m4 source

dot2texi

pgf Enable support for dev-tex/pgf (The TeX Portable Graphic Format)
pstricks Enable pstricks support

dev-util

android-ndk

legacy-toolchains Install legacy toolchains
target-32 Support for 32-bit targets
target-64 Support for 64-bit targets

anjuta

devhelp Enable devhelp integration
glade Build glade plugin for anjuta
packagekit Use packagekit to search for missing tools
terminal Enable terminal plugin based on x11-libs/vte

apitrace

cli Enable command line interface
egl Enable EGL support

buildbot

irc Add support for status delivery through an ircbot.
mail Add support for watching a maildir for commits.
manhole Add support for manhole (debug over ssh)

catalyst

ccache Enables ccache support

cmake

system-jsoncpp Use system copy of dev-libs/jsoncpp instead of bundled one.

coccigrep

vim Install the coccigrep vim plugin

codeblocks

contrib Build additional contrib components

cppcheck

htmlreport install cppcheck-htmlreport

ctags

ada Enable Ada support

cwdiff

a2ps install app-text/a2ps for postscript output
mercurial install hg wdiff alias for dev-vcs/mercurial

devhelp

gedit Install plugin for app-editors/gedit

dialog

minimal Disable library, install command-line program only

emilpro

system-binutils Use the gentoo binutils instead of building against an unpatched vanilla version

fatrace

powertop Add powetop integration

geany

gtk3 Use GTK+3 instead of GTK+2
vte Enable Terminal support (x11-libs/vte)

geany-plugins

autoclose Enable the autoclose plugin.
commander Enable the commander plugin which provides a command panel for rapid access to any action.
debugger Enable the debugger plugin which interfaces with sys-devel/gdb
defineformat Enable the defineformat plugin.
devhelp Enable the devhelp plugin which integrates dev-util/devhelp
enchant Enable spell checking using enchant
gpg Enable geanypg plugin which integrates GPG using app-crypt/gpgme
gtkspell Use gtkspell for dictionary support
markdown Enable the markdown plugin which uses app-text/discount and net-libs/webkit-gtk to display a realtime preview markdown.
multiterm Enable the multiterm plugin
scope Enable the scope plugin which is a graphical GDB front-end
soup Enable updatechecker and geniuspaste plugins which require net-libs/libsoup
webkit Enable webhelper plugin which requires net-libs/webkit-gtk

global

vim Integrate the GNU GLOBAL source code tag system with Vim

google-perftools

debug Build a set of libraries with debug support (so-called debugalloc). These are available by default but are not needed unless you're actually developing using tcmalloc.
largepages Use (experimental) larger pages for tcmalloc, this increases memory usage, but should speed up the allocation/free operations.
minimal Only build the tcmalloc_minimal library, ignoring the heap checker and the profilers.

gtk-doc

highlight Enable source code highlighting
vim Enable source code highlighting through app-editors/vim

intel-ocl-sdk

android Install android related files
system-boost Use system boost (dev-libs/boost) instead of bundled one
system-clang Use system clang (sys-devel/clang) instead of bundled one
system-qt Use system Qt (sys-devel-qtcore, sys-devel/qtgui) instead of bundled one
system-tbb Use sytem Thread Building Blocks (dev-cpp/tbb) instead of bundled one
tools Install Intel Offline Compiler

kdevelop

cmake Enable support for CMake build system
gdbui Enable GUI for attaching GDB to a running process
okteta Enable hex editor plugin
qthelp Enable support for QtHelp documentation browsing
reviewboard Enable reviewboard support

kdevelop-qmake

tools Build and install the qmake-parser debugging tool

kdevplatform

classbrowser Enable the class browser plugin
konsole Enable kde-apps/konsole integration
reviewboard Enable reviewboard support

ltrace

unwind Use sys-libs/libunwind for frame unwinding support

lttng-tools

ust Support LTTng-UST (Userspace Tracing)

metro

ccache Enable support for ccache
git Enable support for git snapshots
threads Enable support for pbzip2 tarball packing/unpacking

mingw64-runtime

idl Install idl files.
libraries Build extra libraries.
tools Build extra tools.

molecule

plugins Add plugins provided by dev-util/molecule-plugins

monkeystudio

plugins Build and install additional plugins

nemiver

memoryview Enable the optional hexadecimal memory inspection with app-editors/ghex.

nsis

config-log Enable the logging facility (useful in debugging installers)

nvidia-cuda-sdk

cuda Build CUDA binaries.
opencl Build OpenCL binaries.

nvidia-cuda-toolkit

debugger Installs the CUDA debugger.
eclipse Install the dev-util/eclipse-sdk plugins
profiler Installs the NVIDIA CUDA visual profiler.

perf

audit Enable support for sys-process/audit.
demangle Enable C++ symbol name demangling, using libbfd from sys-devel/binutils. When this flag is enabled, the package will have to be rebuilt after every version bump of binutils.
doc Build documentation and man pages. With this USE flag disabled, the --help parameter for perf and its sub-tools will not be available. This is optional because it depends on a few documentation handling tools that are not always welcome on user systems.
perl Add support for Perl as a scripting language for perf tools.
unwind Use sys-libs/libunwind for frame unwinding support.

pkgconf

pkg-config Install as a replacement for dev-util/pkgconfig
strict Adhere to POSIX pkg-config specification. Useful for finding uses of non-standard pkg-config invocations.

pkgconfig

internal-glib Use internal copy of dev-libs/glib

pkgconfig-openbsd

pkg-config Install as a replacement for dev-util/pkgconfig

qdevelop

plugins Build and install additional plugins

reviewboard

codebase Enables a build of the docs/codebase folder
manual Enables a build of the docs/manual folder
rnotes Enables a doc build of the release notes

scanmem

gui Enable the GameConqueror GUI

schroot

btrfs Enable support for chroots using btrfs snapshots.
dchroot Enables the building of a wrapper named "dchroot", replacing sys-apps/dchroot.
lvm Enable support for chroots using LVM snapshots.

squashdelta

lz4 Enable support for LZ4 compression using app-arch/lz4

squashmerge

lz4 Enable support for LZ4 compression using app-arch/lz4

strace

aio Enable dev-libs/libaio support for tracing Asynchronous I/O operations

suse-build

symlink Provide compatibility symlinks with original openSUSE package (might clash with other packages)

sysdig

modules Build kernel modules needed for tracing local events. Disable this only if you intend to use sysdig purely to work with dumpfiles.

trace-cmd

udis86 Enable support for dev-libs/udis86 disassembler library

universalindentgui

html Add support for HTML files

dev-vcs

bzr

sftp Enable sftp support

bzr-gtk

gpg Support signing with GnuPG.
nautilus Integrate with Nautilus file manager

cssc

valgrind Enable usage of dev-util/valgrind in tests

cvs

server Enable server support

cvs2svn

bazaar Support for dev-vcs/bzr

darcs

color Use ansi color escapes.
http Use the pure Haskell HTTP package for HTTP support.
network-uri Get Network.URI from the network-uri package.
optimize Build with optimizations (-O2).
terminfo Use the terminfo package for enhanced console support.
threaded Use threading and SMP support.

fossil

json Enable the JSON API of Fossil's wiki
lineedit Enable line-editing with libedit or readline
sqlite Use the system SQLite instead of the bundled one

git

blksha1 Use the new optimized SHA1 implementation
cgi Install gitweb too
curl Support fetching and pushing (requires webdav too) over http:// and https:// protocols
gpg Pull in gnupg for signing -- without gnupg, attempts at signing will fail at runtime!
gtk Include the gitview contrib tool
highlight GitWeb support for app-text/highlight
mediawiki Support pulling and pushing from MediaWiki
ppcsha1 Make use of a bundled routine that is optimized for the PPC arch
subversion Include git-svn for dev-vcs/subversion support
webdav Adds support for push'ing to HTTP/HTTPS repositories via DAV

git-annex

android Building for Android
androidsplice Get TH splices for Android.
asciiprogress Use ascii-progress library (experimental)
assistant Enable git-annex assistant and watch command
cryptohash Enable use of cryptohash for checksumming
desktop-notify Enable desktop environment notifications
dns Enable the haskell DNS library for DNS lookup
ekg Enable use of EKG to monitor git-annex as it runs.
feed Enable podcast feed support
pairing Enable pairing of git annex repositories
production Enable production build (slower build; faster binary)
quvi Enable use of quvi to download videos
s3 Enable Amazon S3 remote
tahoe Enable the tahoe special remote
tdfa Use regex-tdfa for wildcards
testsuite Embed the test suite into git-annex
torrentparser Use haskell torrent library to parse torrent files
webapp Enable git-annex webapp
webapp-secure Secure webapp
webdav Enable webdav remote

gitg

glade Install a glade catalog file
python Install Python bindings for those plugins requiring it.

gitolite

contrib Install user-contributed files
tools Install tools to e.g. convert a Gitosis config to gitolite or one to check if your setup is gitolite >= 3.x compatible

gitolite-gentoo

contrib Install user-contributed files
tools Install tools to e.g. convert a Gitosis config to gitolite or one to check if your setup is gitolite >= 3.x compatible

mercurial

bugzilla Support bugzilla integration.
gpg Support signing with GnuPG.
tk Install dev-lang/tk for hgk script.

qct

bazaar Support for dev-vcs/bzr
mercurial Support for dev-vcs/mercurial
monotone Support for dev-vcs/monotone

rabbitvcs

caja Enable extension for mate-base/caja
cli Eanble console based frontend
diff Use for diff command dev-util/meld
gedit Enable plugin for app-editors/gedit
nautilus Enable extension for gnome-base/nautilus
thunar Enable extension for xfce-base/thunar

subversion

ctypes-python Build and install Ctypes Python bindings
dso Enable runtime module search
extras Install extra scripts (examples, tools, hooks)
http Enable http support using net-libs/serf
webdav-neon Enable WebDAV support using net-libs/neon
webdav-serf Enable WebDAV support using net-libs/serf

games-action

awesomenauts

bundled-libs Use the upstream provided bundled libraries.

beathazardultra

bundled-libs Use the upstream provided bundled libraries.

chromium-bsu

mixer Enables media-libs/sdl-mixer sound backend instead of media-libs/openal one.

d1x-rebirth

demo Use the demo data instead of the full game
linguas_de Provides German translations for the game's briefings, robot descriptions, and outro of the original campaign
music Support for ingame music
opl3-musicpack Include alternate version of the game's music, recorded with the Yamaha YMF262 OPL3 soundchip
sc55-musicpack Include alternate version of the game's music, recorded with the Roland Sound Canvas SC-55 MIDI module

d2x-rebirth

demo Install games-action/descent2-demodata as well
linguas_de Provides German translations for the game's briefings, robot descriptions, and outro of the original campaign
music Support for ingame music
opl3-musicpack Include alternate version of the game's music, recorded with the Yamaha YMF262 OPL3 soundchip
sc55-musicpack Include alternate version of the game's music, recorded with the Roland Sound Canvas SC-55 MIDI module

hotline-miami

bundled-libs Use bundled libraries.
launcher Install qt launcher

minetest

leveldb Enable LevelDB backend
luajit Use dev-lang/luajit instead of dev-lang/lua
redis Enable redis backend via dev-libs/hiredis
server Build minetest server

openlierox

breakpad Compile with support for breakpad crash reporting system

solar2

bundled-libs Use the upstream provided bundled libraries.

super-hexagon

bundled-libs Use the upstream provided bundled libraries.

supertuxkart

fribidi Support for right-to-left languages
wiimote Support for wiimote input devices

swordandsworcery

bundled-libs Use the upstream provided bundled libraries.

trine2

bundled-libs Use bundled libraries.
launcher Install gtk+ launcher

games-arcade

bomns

editor enables building the level editor

burgerspace

network Enable client-server support

commandergenius

tremor Use media-libs/tremor as ogg decoder instead of media-libs/libvorbis

jumpnbump

music Enable playing of background music

lbreakout2

themes Install additional themes

moleinvasion

music Download and install the music files

performous

midi Enable MIDI I/O support
songs Install a few demo songs
tools Install tools
webcam Enable Webcam support

slimevolley

net Enable network support

smc

music Download and install the music files

tuxanci

physfs Use dev-games/physfs instead of dev-libs/libzip to load compressed data
sound Enable sound

games-board

cockatrice

server Compile server support

crafty

no-opts Don't try to enable crazy CFLAG options

freedoko

backgrounds Install additional background images
gnomecards Install the gnome-games card set
kdecards Install the KDE card set
net Enable network game support
openclipartcards Install the openclipartcards card set
pysolcards Install the PySol card set
xskatcards Install the XSkat card set

grhino

gtp Install the GTP (Go/Game Text Protocol) frontend

pasang-emas

extras Install some extra themes

pioneers

help Enable gnome ingame help via scrollkeeper

pysolfc

extra-cardsets Install extra cardsets
sound Enable sound support using dev-python/pygame

spider

athena Enable athena widgets

stockfish

armv7 Build for armv7; enables PIE
general-32 Generic unoptimized 32-bits build
general-64 Generic unoptimized 64-bits build
optimize Enable upstream -O3 optimizations (default enabled)

xboard

default-font Install the default font that xboard uses
zippy Enable experimental zippy client

games-emulation

dolphin

lto Add support for link-time optimizations.

generator

sdlaudio Enable SDL Audio

higan

profile_accuracy Compile a binary optimized for accuracy
profile_balanced Compile a binary with balanced optimization
profile_performance Compile a binary optimized for performance
udev Enable udev based input

mednafen

debugger Build with internal debugger
pax_kernel Triggers a paxmarking of the binary

mupen64plus

audio-sdl Enable SDL audio plugin.
input-sdl Enable SDL input plugin.
rsp-hle Enable HLE RSP plugin.
ui-console Enable default console UI.
ui-m64py Enable PyQt4 UI using games-emulation/m64py.
video-glide64mk2 Enable Glide64mk2 video plugin.
video-rice Enable Rice video plugin.

mupen64plus-core

new-dynarec Enable new experimental dynamic recompiler implementation (only for x86 and arm)
osd Overlay emulator messages using on-screen-display

mupen64plus-video-glide64mk2

hires Support hi-resolution textures (requires dev-libs/boost)

pcsxr

cdio Use libcdio for CD support
sdl Use SDL sound backend (other parts of SDL are used unconditionally)

snes9x

netplay Enable playing ROMs over the network (not recommended)
xrandr Enable support for the X xrandr extension

vbam

link Enable GBA linking functionality

yabause

pic disable optimized assembly code that is not PIC friendly

zsnes

debug Enable the builtin debugger
pax_kernel Triggers a paxmarking of the binary

games-engines

frobtads

tads2compiler Build TADS2 compiler
tads3compiler Build TADS3 compiler

odamex

master Build master server target (advertises odamex server list)
odalaunch Build the wxwidgets based launcher.
portmidi Enable portmidi support.
server Build server target.

openmw

devtools Install development tools like bsatool, esmtool and opencs.
launcher Install the launcher for configuring OpenMW.

renpy

development Install IDE for game developers and an empty game template

scummvm

fluidsynth compile with support for fluidsynth
mpeg2 enable mpeg2 codec for cutscenes
unsupported enable unsupported and/or broken game engines (you're on your own)

solarus

doc Install doxygen developer documentation.
luajit Use LuaJIT instead of default Lua.

games-fps

alienarena

vidmode Link against x11-libs/libXxf86vm. Required for full-screen support.

darkplaces

cdsound Enables using CD audio in the engine
demo Uses the demo data from quake1 (quake1-demodata)
lights Install and setup the updated light maps
textures Install and setup the updated textures

doom-data

doomsday Add wrapper to run it within doomsday

doom3

dedicated install only as a dedicated game server
roe Adds support for the Resurrection of Evil expansion

doomsday

demo Install launcher dor doom1.wad from games-fps/doom-data
doom Install launcher for jdoom game
fluidsynth Build the FluidSynth sound driver
freedoom Install launcher for doom1.wad from games-fps/freefoom
heretic Install launcher for jheretic game
hexen Install launcher for jhexen game
resources Enable support for games-fps/doomsday-resources in jdoom launcher
snowberry Install Snowberry doomsday front-end
tools Build additional tools such as doomsday-shell, md2tool and texc

duke3d

demo Install the demo files
pic disable optimized assembly code that is not PIC friendly

duke3d-data

gog Extract the data from the GOG.com installer.

eduke32

demo Install games-fps/duke3d-demodata as well
gtk Compile with gtk launcher
offensive Include optional XXX texture pack (needs USE 'textures')
opl-musicpack Include optional OPL (AdLib) music pack
samples Install samples
sc55-musicpack Include optional Roland SC-55 music pack
server Compile with server support
textures Include optional high-resolution textures (needs USE 'opengl')
tools Build several tools for modding and development
vpx Enable support for WebM VP8 Codecs (needs USE 'opengl')

lsdldoom

freedoom Install games-fps/freedoom wad file
net Enables network game support
shareware Install games-fps/doom-data for shareware wad file

nexuiz

maps Install the community map pack

quake2-icculus

demo Install the demo files (quake2-demodata) and configure for use
qmax Build the pretty version (quake max)
rogue Build support for the 'Ground Zero' Mission Pack (rogue)
xatrix Build support for the 'The Reckoning' Mission Pack (xatrix)

quake3

mumble Adds player-location (positional audio) support to VoIP
teamarena Adds support for Team Arena expansion pack
voice Adds VoIP support

quake3-bin

teamarena Adds support for Team Arena expansion pack

quake3-demo

dedicated install only as a dedicated game serer

quakeforge

wildmidi enable libWildMidi support
xdg enable XDG support

qudos

demo Install the demo files (quake2-demodata) and configure for use
mods Build support for the quake2 mission packs
qmax Build the pretty version (quake max)
textures Install the enhanced textures (quake2-textures)

rott

demo Install the shareware version

sauerbraten

server Compile server support

turtlearena

mumble Adds player-location (positional audio) support to VoIP
server Build server target
voice Adds VoIP support

unreal-tournament-goty

S3TC Add the extra fancy textures to UT ... only works on certain cards (nvidia/ati/s3)

urbanterror

altgamma Clearskies - X11-based gamma for Linux
pax_kernel Triggers a paxmarking of the binary
server Build server target

warsow

irc Enable IRC support
server Build server binaries additionally

worldofpadman

maps Install extra maps (PadPack)

xonotic

ode Enable support for physics engine from dev-games/ode

games-kids

crayon-physics

bundled-libs Use the upstream provided bundled libraries.

games-misc

katawa-shoujo

system-renpy Use games-engines/renpy instead of the bundled one (experimental)

little-inferno

bundled-libs Use bundled libraries.

xcowsay

fortune Installs the fortune-mod xcow binary

games-mud

tf

atcp enable ATCP support.
gmcp enable GMCP support.
option102 enable telnet option 102 support.

games-puzzle

cuyo

music Enable playing of background music

jag

editor Install level editor

nightsky

bundled-libs Use the upstream provided bundled libraries.

pingus

music Enable playing of background music

tiny-and-big

bundled-libs Use the upstream provided bundled libraries.

xlogical

alt_gfx Use alternate graphics which are closer to the original Amiga version

games-roguelike

FTL

bundled-libs Use bundled libraries.

angband

sound Enable and install sounds

stone-soup

luajit Use dev-lang/luajit as scripting backend instead of dev-lang/lua.
ncurses Enable for console (uses ncurses) based build. (can be enabled on top of tiles)
tiles Enable for graphical (tiled) build. (can be enabled on top of ncurses)

tomenet

server Compile server support

games-rpg

a-bird-story

bundled-libs Use bundled libraries

arx-fatalis-data

gog Extract the data from the GOG.com installer.

arx-libertatis

c++0x Build ROOT using the C++11 standard.
crash-reporter Build a dev-qt/qtgui-based tool that allows to submit crash information to the upstream backtracker.
debug Enable asserts and debug logging.
static Link libraries statically, currently only media-libs/glew
tools Build tools that can extract the game's data and save files.
unity-build Build everything in one big source file, allowing for faster build times and better optimizations at the cost of higher memory usage.

daimonin-client

music Install extra music

drascula

sound Install optional audio files

dreamweb

doc High-resolution scans of the written material in the original UK game box

dungeon-defenders

bundled-libs Use the upstream provided bundled libraries.

eternal-lands-data

bloodsuckermaps Will install Bloodsucker's Maps in place of the official map files.
music Adds in-game music.
sound Adds in-game sound effects.

grimrock

bundled-libs Use bundled libraries.

kqlives

cheats Enable cheating mode

nwn

hou Install the Hordes of the Underdark expansion pack
sou Installs the Shadows of Undrentide expension pack

nwn-data

hou Install the Hordes of the Underdark expansion pack
nowin For those people who cant grab the 1.2 gigs of data files from a windows partition
sou Installs the Shadows of Undrentide expension pack

sumwars

tools Builds editor tools

to-the-moon

bundled-libs Use bundled libraries

valyriatear

editor Compile the Qt editor along with the game

games-simulation

corsix-th

ffmpeg Use ffmpeg for playing in-game cutscenes.
mapeditor Build the map editor (needs opengl enabled!).
midi Use SDL mixer and timidity for in-game music.
opengl Use OpenGL for rendering.
sdl Use SDL for rendering.
sound Use SDL mixer for in-game sound.
truetype Use high quality fonts.

flightgear

dbus Enable screensaver DBus interaction
jsbsim Enables JSBSim Flight Dynamics Model (default)
oldfdm Enables deprecated Flight Dynamics Models (LaRCsim, UIUC)
qt5 Builds Qt5 launcher application
udev Enables event-based Input devices through virtual/udev
utils Builds various utilities (fgpanel, terrasync, fgviewer among others)
yasim Enables YASim Flight Dynamics Model

openttd

aplaymidi Enables midi music in game, using aplaymidi as an external player
dedicated Build only the openttd server, and not the client.
lzo Enables LZO compression for savegames. This is only needed to load extremely old savegames. (versions before 0.2)
openmedia Enables the free open media sets: OpenGFX, OpenSFX, OpenMSX, removing the requirement for proprietary TTD assets to play OpenTTD.

singularity

music Install music files

games-sports

speed-dreams

xrandr Enable support for the X xrandr extension

xmoto

editor Depend on inkscape, scripts to convert svg to level (svg2lvl)

games-strategy

0ad

editor Include Atlas scenario editor projects
lobby Enable the use of net-libs/gloox and the multiplayer lobby
nvtt Support for some uncompressed data formats via media-gfx/nvidia-texture-tools (might be needed for some mods)

defcon-demo

system-libs Use system libraries instead of the ones included in the upstream distribution.

freeciv

aimodules Support for dynamically loadable AI modules (server-side)
auth Add authentication capability via mysql, postgres or sqlite3
mapimg Additional mag image toolkit via media-gfx/imagemagick
modpack Build the freeciv-modpack-program to download/install mods
server Enable server support. Disabling this will also make it impossible to start local games.
sound Add support for sound provided by media-libs/sdl-mixer
system-lua Use dev-lang/lua instead of the bundled liblua

freeorion

cg Add support for NVIDIA toolkit plugin

freesynd

devtools Build development tools

heroes3

maps Installs optional map data
music Installs optional music data
sounds Installs optional sound data

ja2-stracciatella

editor Adds necessary file to run the editor
linguas_ru_gold Support for russian gold ja2 version

liquidwar6

doc Convert the info pages to html
gles2 Enable OpenGL ES 2.0 support
gtk Used to display error/critical messages
maps Install extra maps
ogg Enable mod-ogg via media-libs/sdl-mixer (currently the only sound provider)
readline Enable interactive script shell for hacking

megaglest

editor Build map editor
fribidi Enable FriBIDi support
model-viewer Build model viewer
streflop Use the library streflop. Out of synchs may occur if not enabled.
tools Build model import/export tools
unicode Use unicode strings for wxwidgets
wxuniversal Use the wxUniversal port which implements the various GUI controls by drawing them itself

naev

mixer Enables media-libs/sdl-mixer sound backend in addition to media-libs/openal one.

openra

cg NVIDIA toolkit plugin
tools Install some development tools such as editor.

s25rttr

glfw Compile another video driver based on media-libs/glfw.

seven-kingdoms

network Enable support for multiplayer via media-libs/sdl-net

ufo-ai

editor Build map editor

uqm

music download and install music files (large)
remix download and install music remix files (large)
voice download and install voice files (large)

warzone2100

qt4 Use qt-gui/qt-opengl for backend rendering instead of sdl

wesnoth

fribidi Support for right-to-left languages
server Enable compilation of server

games-util

gslist

web Enable the web interface

pyfa

graph Enable support for graphs

wit

fuse Enable image mount support via fuse

gnome-base

gconf

ldap Build backend which enables default mail accounts, addressbooks and calendars for Evolution to be configured using each user's LDAP entry."

gdm

audit Enable support for sys-process/audit
fprint Enables experimental fingerprint authentication using sys-auth/fprintd
plymouth Enable support for smooth transition from sys-boot/plymouth

gnome

classic Install gnome-extra/gnome-shell-extensions for the Gnome Shell Classic mode
extras Install additional GNOME applications

gnome-common

autoconf-archive Pull in sys-devel/autoconf-archive for ax_*.m4 files instead of installing them from the gnome-common tarball

gnome-control-center

colord Support color management using x11-misc/colord
gnome-online-accounts Enable configuration panel for net-libs/gnome-online-accounts accounts
i18n Enable support for enhanced input methods through app-i18n/ibus

gnome-desktop

license-docs Install help files documenting GNOME's licenses

gnome-extra-apps

games Install Gnome Games
share Install the gnome-extra/gnome-user-share personal file sharing tool
shotwell Install the media-gfx/shotwell photo manager
tracker Install the app-misc/tracker indexer and the GNOME packages that require it

gnome-keyring

ssh-agent Use GNOME Keyring to unlock SSH keys. Recommended unless you are using ECDSA or Ed25519 keys.

gnome-light

gnome-shell Install gnome-base/gnome-shell and x11-wm/mutter for the standard GNOME 3 desktop mode

gnome-session

gconf Optional support for gnome-base/gconf configuration storage system

gnome-settings-daemon

colord Support color management using x11-misc/colord
openrc-force Skip systemd dependency (#480336), enabling this flag will become your setup to be fully unsupported by upstream and downstream Gnome team. Do not try to enable it unless completely needed
short-touchpad-timeout Change the touchpad timeout so that it's effective for fast typists

gnome-shell

i18n Enable support for enhanced input methods through app-i18n/ibus
openrc-force Skip systemd dependency (#480336), enabling this flag will become your setup to be fully unsupported by upstream and downstream Gnome team. Do not try to enable it unless completely needed

gvfs

afp Enables support for accessing AFP (Apple Filing Protocol) network shares
archive Enables support for accessing files in archives transparently via app-arch/libarchive
bluray Enable playback of Blu-ray filesystems using media-libs/libbluray
fuse Enables fuse mount points in $HOME/.gvfs for legacy application access
gnome-online-accounts Enable configuration panel for net-libs/gnome-online-accounts accounts
http Enable the HTTP/DAV backend using net-libs/libsoup-gnome
libsecret Enable app-crypt/libsecret support to store login credentials.
nfs Enable NFS client support via net-fs/libnfs.
udev Enable udev base replacement code for cdda feature

libglade

tools Install libglade-convert Python script.

libgnome-keyring

vala Enable bindings for dev-lang/vala

libgnomecanvas

glade Enable glade support

libgtop

introspection Use dev-libs/gobject-introspection for introspection

librsvg

tools Build svg viewer tool

nautilus

packagekit Use packagekit to search for programs to open unknown file types
previewer Use gnome-extra/sushi to preview files from the file mananger
sendto Enable the nautilus-sendto extension to send files to various locations/devices
tracker Add support for app-misc/tracker search

orbit

pic Force libname-server-2 to be built as PIC; needed on hardened systems

gnome-extra

avant-window-navigator

gconf Enable GConf as configuration backend

avant-window-navigator-extras

gconf Enable GConf as configuration backend

cinnamon-control-center

colord Support color management using x11-misc/colord

cinnamon-settings-daemon

colord Support color management using x11-misc/colord

evolution-data-server

api-doc-extras Build documentation for private APIs
gnome-online-accounts Enable using net-libs/gnome-online-accounts for authorization
weather Enable optional weather calendar support

gdesklets-core

dbus Enable gDesklets Controls to use DBus

gnome-boxes

usbredir Use sys-apps/usbredir to redirect USB devices to another machine over TCP

gnome-color-manager

packagekit Enable support for the distro-neutral package manager GUI app-admin/packagekit

gnome-commander

chm Enable metadata support for Microsoft Compiled HTML Help files
gsf Add metadata support for OLE, OLE2 and ODF
pdf Add metadata support for PDF
python Add support for python plugins"
taglib Add metadata support for ID3, Vorbis, FLAC and APE

gnome-do-plugins

banshee Enables the Banshee (media-sound/banshee) plugin

gnome-dvb-daemon

totem Build a plugin for media-video/totem
vala Add support for dev-lang/vala

gnome-system-monitor

systemd Display sys-apps/systemd metadata, e.g. unit names, for running processes

gucharmap

vala Enable bindings for dev-lang/vala

libgda

canvas Enable support for x11-libs/goocanvas
http Enable embedded net-libs/libsoup based server
json Enable support for JSON format
libsecret Enable app-crypt/libsecret support to store login credentials
mdb Enable support for Microsoft Access database using app-office/mdbtools
reports Install tools for generating graphical reports
sourceview Enable support for x11-libs/gtksourceview

libgsf

gtk Enable use of gdk in thumbnailer

nemo

l10n Pull in gnome-extra/cinnamon-translations for localization support
packagekit Use packagekit to search for programs to open unknown file types
tracker Add support for app-misc/tracker search

nm-applet

gconf Build tool for migrating gconf settings from nm-applet-0.8.x
modemmanager Enable support for mobile broadband devices using net-misc/modemmanager

sushi

office Support viewing file formats such as generated by app-office/libreoffice

synapse

plugins Build support for plugins using librest
zeitgeist Add support for Zeitgeist event tracking system

zeitgeist

datahub Use build datahub for passive event injection
downloads-monitor Monitor the XDG_DOWNLOAD_DIRECTORY
extensions Use gnome-extra/zeitgeist-extentions to enhance the internal routines
fts Enable the full text search extension
plugins Use gnome-extra/zeitgeist-datasources to enable numerous packages to inject events
sql-debug Enable SQL debugging
telepathy Enable telepathy framework as data source

zeitgeist-datahub

download Monitor XDG download directory
telepathy Telepathy logging support for 1-to-1 chats, calls and file transfers

zeitgeist-datasources

bzr Zeitgeist plugin for dev-vcs/bzr as data source
chromium Zeitgeist plugin for www-client/chromium as data source
emacs Zeitgeist plugin for emacs as data source
firefox Zeitgeist plugin for www-client/firefox as data source
geany Zeitgeist plugin for dev-util/geany as data source
telepathy Zeitgeist plugin for telepathy framework as data source
thunderbird Zeitgeist plugin for mail-client/thunderbird as data source
tomboy Zeitgeist plugin for app-misc/tomboy as data source
vim Zeitgeist plugin for vim as data source

zeitgeist-extensions

fts Enable the full text search
geolocation Add the physical location of the computer at the moment when events are inserted
memprofile Memory profiling extension
sqldebug debug zeitgeists sql statements
tracker Notify Tracker on events

gnustep-apps

gemas

projectcenter Build and install plugin for gnustep-apps/projectcenter

gnumail

emoticon Enable extra Emoticon Bundle to see smiley's in e-mail messages

gworkspace

gwmetadata Enable the metadata indexing and searching system

gnustep-base

gnustep-back-art

xim Enable X11 XiM input method

gnustep-back-cairo

xim Enable X11 XiM input method

gnustep-back-xlib

xim Enable X11 XiM input method

gnustep-gui

speech Audio support using app-accessibility/flite

gnustep-make

libobjc2 Enables use of the GNUstep Objective-C runtime (gnustep-base/libobjc2) with non-fragile ABI and sys-devel/clang compiler
native-exceptions Enables use of the native Objective-C exception support (@try/@catch/@finally) built-in objective-c exceptions with compilers that support it

libobjc2

boehm-gc Enable Hans Boehm's garbage collector (dev-libs/boehm-gc). Not recommended by upstream

kde-apps

ark

archive Enable support for a variety of archive formats through libarchive

cantor

R Enable dev-lang/R backend support
analitza Enable kde-base/analitza backend support
qalculate Enable sci-libs/libqalculate backend support

dolphin

thumbnail Enables video thumbnail generation

dolphin-plugins

bazaar Enable support for the bazaar VCS
mercurial Enable support for the mercurial VCS

gwenview

kipi Support for the KDE Image Plugin Interface.

kaccessible

speechd Enable support for the speech-dispatcher speech synthesizer

kalzium

editor Enable the embedded molecule editor/viewer
solver Enable the equation solver

kdeadmin-meta

cron Installs KDE application for virtual/cron configuration

kdeartwork-kscreensaver

eigen Enable various arithmetic screensavers which use Eigen2 for computations.
kexiv2 Enable image rotation based on exif tags with libkexiv2.

kdebase-data

wallpapers Install the KDE wallpapers

kdebase-kioslaves

sftp Enable SFTP protocol support using net-libs/libssh

kdebase-meta

display-manager Pull in a graphical display manager
wallpapers Install the KDE wallpapers

kdebase-runtime-meta

crash-reporter Builds a gui tool to submit crash information to the upstream backtracker
nepomuk Enable Nepomuk based semantic desktop support (deprecated)

kdenetwork-meta

ppp Enable support for net-dialup/ppp.

kdeutils-meta

floppy Install kde-base/kfloppy to format and create DOS or ext2fs filesystems in a floppy.

kget

bittorrent Enable bittorrent transfer plugin through net-libs/libktorrent
gpg Support for signature verificatopm by QGpgME via kde-base/kdepimlibs
mms Enable MMS (Microsoft Media Server) plugin through media-libs/libmms
nepomuk Enable Nepomuk based semantic desktop support (deprecated)
webkit Enable KdeWebkit browser plugin using kde-misc/kwebkitpart

kig

scripting Support Python scripting

kmix

canberra Enable sound event support using media-libs/libcanberra

konqueror

bookmarks Add dependency on bookmark package.

kopete

addbookmarks Automatically add incoming urls to bookmarks.
autoreplace Automatically replace selected text
contactnotes Enables writing personal notes for contacts.
gadu Enable the Gadu protocol handler.
groupwise Enable the Groupwise protocol handler.
highlight Allows you to specify highlights on specific events.
history Enables saving chat history.
latex Embed latex formatted text into messages.
meanwhile Enable the Sametime protocol handler.
nowlistening Shows song you currently listen to in your status/etc. Bindings for many players.
otr Allows crypting your chat (drugs and talking nonsense are considered as good alternatives ;]).
pipes Send messages to external pipe.
privacy Filter for incoming messages
skype Enable Skype protocol handler (not fully functional yet).
sms Enable SMS sendinge functionality.
statistics Everybody loves statistic graphs, especially cake ones. ;]
testbed Enable the testbed protocol.
texteffect Various fancy text effects for your messages (don't ever consider writing us with this enabled ;]).
translator Translate incoming and outgoing messages.
urlpicpreview Enables in conversation pictures preview.
webpresence Show your status and some more information on web.
winpopup Enable pop-up messages sending on windows. (same as good old "net send" messages ;])
yahoo Enable yahoo protocol support.
zeroconf Enable Link-Local Messaging via the bonjour protocol.

krdc

rdesktop Enable runtime dependency for net-misc/rdesktop
telepathy Enable desktop sharing through a telepathy client

krfb

ktp Enable displaying of KDE Telepathy contacts
telepathy Enable desktop sharing through a telepathy client

ksnapshot

kipi Support for the KDE Image Plugin Interface.

kstars

fits Enable support for the FITS image format through cfitsio
indi Enable support for Astronomical control library using libindi

kwalletd

gpg Support wallets with GnuPG encryption additionally to default blowfish-encrypted file

lokalize

nepomuk Enable Nepomuk based semantic desktop support (deprecated)

marble

designer-plugin Enable designer plugin
phonon Enable sound support via media-libs/phonon
shapefile Enable support for ESRI shapefiles
zip Enable support for reading and displaying .kmz files

okular

chm Enable support for Microsoft Compiled HTML Help files
dpi DPI detection support for PDF rendering via x11-libs/libkscreen
ebook Add E-Book support
mobi Add mobipocket support

oxygen-icons

sources Additionally install the svg sources of the bitmap icons (needed for redistribution)

poxml

extras Build po2xml and swappo tools

step

qalculate Enable the libqalculate library for unit conversion

kde-base

kactivities

nepomuk Enable Nepomuk based semantic desktop support (deprecated)

kde-meta

kdepim Pull in KDE PIM
sdk Pull in developer-specific meta-packages

kdebase-startkde

wallpapers Install the KDE wallpapers

kdebindings-meta

csharp Enable C# language bindings for KDE and Qt

kdelibs

nepomuk Enable Nepomuk based semantic desktop support (deprecated)
opengl Enable OpenGL support for Plasma (GLApplet)

kdepim-common-libs

google Google service integration via net-libs/libkgapi

kdepim-meta

akonadi Enables support for kde-base/akonadi

kdepim-runtime

facebook Facebook service integration via net-libs/libkfbapi
google Google service integration via net-libs/libkgapi

kdepimlibs

prison Enable support for QRcodes in contacts

kdeplasma-addons

attica Enable support for dev-libs/libattica
desktopglobe Enable Desktop Globe wallpaper using kde-base/marble
fcitx Use fcitx input method via app-i18n/fcitx
ibus Use ibus input method via app-i18n/ibus
json Enable JSON support via dev-libs/qjson
kdepim KDE PIM integration via kde-base/kdepimlibs
nepomuk Enable Nepomuk based semantic desktop support (deprecated)
oauth Enable OAuth support via dev-libs/qoauth
qalculate Enable Qalculate runner using sci-libs/libqalculate
qwt Enable applets that use x11-libs/qwt:5
scim Enable applets that use app-i18n/scim

kdm

consolekit Enables support for authorization using consolekit

kfilemetadata

epub Adds support for reading EPUB ebook metadata
mobi Adds support for reading MOBI ebook metadata

kimono

akonadi Compile bindings for Akonadi
nepomuk Compile bindings for Nepomuk
plasma Compile bindings for KDE's Plasma

klipper

prison Enable support for barcodes/QRcodes

korundum

akonadi Compile bindings for Akonadi
kate Compile bindings for KDE Advanced Text Editor
nepomuk Compile bindings for Nepomuk
okular Compile bindings for kde-base/okular

kwin

gles Enable support for GLES.

libplasmaclock

kdepim KDE PIM integration via kde-base/kdepimlibs

nepomuk-core

epub Adds support for reading EPUB ebook metadata
migrator Installs a kde-base/baloo migration tool

perlkde

akonadi Compile bindings for Akonadi
attica Compile bindings for dev-libs/libattica
kate Compile bindings for KDE Advanced Text Editor
nepomuk Compile bindings for Nepomuk
okular Compile bindings for kde-base/okular

perlqt

declarative Compile bindings for dev-qt/qtdeclarative.
multimedia Compile bindings for dev-qt/qtmultimedia.
phonon Compile bindings for Phonon.
qimageblitz Compile bindings for media-libs/qimageblitz.
qscintilla Compile bindings for x11-libs/qscintilla.
qthelp Compile bindings for QtHelp from dev-qt/qthelp.
qwt Compile bindings for x11-libs/qwt.
webkit Compile bindings for dev-qt/qtwebkit.

plasma-workspace

json Enable JSON support via dev-libs/qjson
kdepim KDE PIM integration via kde-base/kdepimlibs
nepomuk Enable Nepomuk based semantic desktop support (deprecated)
qalculate Enable Qalculate runner using sci-libs/libqalculate

powerdevil

pm-utils Adds support for suspend/resume the system through sys-power/pm-utils

pykde4

akonadi Compile bindings for Akonadi
nepomuk Compile bindings for Nepomuk

qtruby

declarative Compile bindings for dev-qt/qtdeclarative.
phonon Compile bindings for Phonon.
qscintilla Compile bindings for x11-libs/qscintilla.
qwt Compile bindings for x11-libs/qwt.
webkit Compile bindings for dev-qt/qtwebkit.

qyoto

phonon Compile bindings for Phonon.
qscintilla Compile bindings for x11-libs/qscintilla.
webkit Compile bindings for dev-qt/qtwebkit.

smokekde

akonadi Compile bindings for Akonadi
attica Compile bindings for dev-libs/libattica
kate Compile bindings for KDE Advanced Text Editor
nepomuk Compile bindings for Nepomuk
okular Compile bindings for kde-base/okular

smokeqt

declarative Compile bindings for dev-qt/qtdeclarative.
multimedia Compile bindings for dev-qt/qtmultimedia.
phonon Compile bindings for Phonon.
qimageblitz Compile bindings for media-libs/qimageblitz.
qscintilla Compile bindings for x11-libs/qscintilla.
qthelp Compile bindings for QtHelp from dev-qt/qthelp.
qwt Compile bindings for x11-libs/qwt.
webkit Compile bindings for dev-qt/qtwebkit.
xmlpatterns Compile bindings for dev-qt/qtxmlpatterns.

systemsettings

kscreen Use kde-misc/kscreen for screen management
nepomuk Enable Nepomuk based semantic desktop support (deprecated)

kde-frameworks

kdesignerplugin

designer Build KF5 widgets plugin for QtDesigner
webkit Build kdewebkit plugin for QtDesigner

kimageformats

eps Support the EPS graphics file format

kinit

caps Capabilities support for improved security and better OOM handling

knotifyconfig

phonon Add sound support via media-libs/phonon

kxmlgui

attica Enable support for kde-frameworks/attica

networkmanager-qt

teamd Enable Teamd control support

plasma

egl Enable EGL support

sonnet

aspell Enable the app-text/aspell spell-checking backend
hunspell Enable the app-text/hunspell spell-checking backend

kde-misc

kcm-grub2

hwinfo Used to work out supported framebuffer resolutions
imagemagick Create splash images compatible with GRUB2
packagekit Add support for packagekit integration

kepas

oscar Enables ICQ (AIM) support.

krusader

bookmarks Add dependency on bookmark package.

networkmanagement

openconnect Build support for the OpenConnect VPN client

plasma-nm

modemmanager Enable support for mobile broadband devices
openconnect Build support for the OpenConnect VPN client

tellico

addressbook Add support for kdepim addressbook (kabc)
nepomuk Enable Nepomuk based semantic desktop support (deprecated)

kde-plasma

kdeplasma-addons

ibus Use ibus input method via app-i18n/ibus
scim Enable applets that use app-i18n/scim

kfilemetadata

epub Adds support for reading EPUB ebook metadata

kinfocenter

egl Retrieve information about OpenGL via EGL
gles Show OpenGL ES information in kinfocenter
nfs Show information about NFS mounts, shares and log entries
pci Show advanced PCI information
samba Show information about Samba mounts, shares and log entries

kio-extras

phonon Enable file audio preview plugin using media-libs/phonon
sftp Enable SFTP protocol support using net-libs/libssh

kmenuedit

hotkeys Enable support for hotkey editing

kwin

gles2 Use OpenGL ES 2 instead of full GL

libksysguard

processui Enables the Interface to view process libs.

plasma-desktop

gtk2 Add support for gtk+2-based applications using legacy xembed systray icons via libappindicator.
gtk3 Add support for gtk+3-based applications using legacy xembed systray icons via libappindicator.
legacy-systray Add support for applications using legacy xembed systray icons.
touchpad Enable configuration module for synaptics-based touchpads.

plasma-meta

display-manager Pull in a graphical display manager
sddm Pull in the x11-misc/sddm display manager and KCM
wallpapers Install the KDE wallpapers

plasma-nm

modemmanager Enable support for mobile broadband devices
openconnect Build support for the OpenConnect VPN client
teamd Enable Teamd control support

plasma-workspace

drkonqi Enables DrKonqi, the KDE crash handler
prison Enable support for barcodes/QRcodes
qalculate Enable Qalculate runner using sci-libs/libqalculate
systemmonitor Enables the system monitor dialog for the Plasma workspace

lxde-base

lxdm

consolekit Enables support for authorization using consolekit
gtk3 Use GTK+3 instead of 2

lxqt-base

lxqt-meta

admin Install app-admin/lxqt-admin
filemanager Install x11-misc/pcmanfm-qt file manager
icons Install an icon theme
lightdm Install x11-misc/lightdm display manager
lximage Install media-gfx/lximage-qt image viewer
minimal Do not install x11-wm/openbox window manager
oxygen Prefer kde-apps/oxygen-icons (default)
powermanagement Install lxqt-base/lxqt-powermanagement package
sddm Install x11-misc/sddm display manager
ssh-askpass Install net-misc/lxqt-openssh-askpass user password prompt tool

lxqt-panel

clock Build clock plugin
colorpicker Build colorpicker plugin
cpuload Build cpuload plugin
desktopswitch Build desktopswitch plugin
dom Build dom plugin
kbindicator Build kbindicator plugin
mainmenu Build mainmenu plugin
mount Build mount plugin
networkmonitor Build networkmonitor plugin
quicklaunch Build quicklaunch plugin
screensaver Build screensaver plugin
sensors Build sensors plugin
showdesktop Build showdesktop plugin
sysstat Build sysstat plugin
taskbar Build taskbar plugin
teatime Build teatime plugin
tray Build tray plugin
volume Build volume plugin
worldclock Build worldclock plugin

mail-client

alot

doc Install user manual and API documentation

alpine

chappa enhance alpine by applying Eduardo Chappa's patches
onlyalpine installs only the alpine binary, so it does not collied with app-editors/pico and/or mail-client/pine
passfile Adds support for caching passwords into a file between sessions
smime Enable support for S/MIME
topal Enable support for net-mail/topal

balsa

crypt Adds support for GnuPG encryption
gtkhtml Use gtkhtml for HTML rendering
gtkspell Use gtkspell for dictionary support
rubrica Adds support for app-office/rubrica addressbook

claws-mail

archive Enable archiving plugin
bogofilter Build mail-filter/bogofilter plugin
dillo Enables support for inline HTTP email viewing with a plugin (which depends on the www-client/dillo browser)
gdata Enable plugin for access to Google data providers
gtk3 Build support for GTK+3
libcanberra Enable sound notification in connection with USE=notification
libindicate Enable notification through DBUS in connection with USE=notification
libnotify Enable notification on the desktop in connection with USE=notification
notification Notification for new mail in different way, see also USE flags libcanberra, libindicate and libnotify
pgp Enable PGP support
smime Build plugin for S/MIME support
spam-report Enable plugin for spam reporting to various services
spamassassin Build mail-filter/spamassassin plugin
valgrind Add support for memory debugging using valgrind

evolution

bogofilter Build mail-filter/bogofilter plugin
crypt Enable GPG encryption support using app-crypt/gnupg and app-crypt/pinentry
highlight Enable text highlighting plugin
ldap Enable support for fetching contacts from an LDAP or Active Directory server using net-nds/openldap
map Enable support for displaying contacts on a map inside evolution using media-libs/libchamplain
spamassassin Build mail-filter/spamassassin plugin
weather Enable optional weather calendar support

mail-notification

sylpheed Enable support for MH mailboxes used by mail-client/sylpheed

mutt

gpg Enable support for app-crypt/gpgme
pop Enable support for pop
sidebar Use the vanilla tree + sidebar patch
smime Enable support for smime
smtp Enable support for smtp
tokyocabinet Enable tokyocabinet database backend for header caching

nail

kerberos If network is enabled, this adds support for GSSAPI login on IMAP through virtual/kerberos.
net Enable support for network protocols (POP, IMAP and SMTP). If you only need to send mail with the local Transport Agent, disabling this will get you support for only /usr/sbin/sendmail call.
ssl If network is enabled, this adds support for S/MIME and SSL/TLS-powered protocols through dev-libs/openssl.

squirrelmail

filter Enable mail-filter/amavisd-new filtering

sylpheed

oniguruma Use dev-libs/oniguruma for regular expression

thunderbird

bindist Disable official Thunderbird branding (icons, name) which are not binary-redistributable according to upstream.
crypt Enable encryption support with enigmail
custom-optimization Fine-tune custom compiler optimizations (-Os, -O0, -O1, -O2, -O3)
gstreamer-0 Use gstreamer:0.10 instead of gstreamer:1 for media support
jemalloc3 Enable or disable jemalloc3 (forced-on when supported prior to 38.0)
lightning Enable app-global calendar support (note 38.0 and above bundles calendar support when this flag is off)
minimal Remove the software development kit and headers
mozdom Enable Mozilla's DOM inspector
system-cairo Use the system-wide x11-libs/cairo instead of bundled.
system-icu Use the system-wide dev-libs/icu instead of bundled.
system-jpeg Use the system-wide media-libs/libjpeg-turbo instead of bundled.
system-libvpx Use the system-wide media-libs/libvpx instead of bundled.
system-sqlite Use the system-wide dev-db/sqlite installation with secure-delete enabled

thunderbird-bin

crashreporter Enable crash reporter for bugs

trojita

password Store passwords securely via dev-libs/qtkeychain

mail-filter

MailScanner

exim Set mail-mta to used MTA
postfix Set mail-mta/postfix to used MTA
spamassassin Enable usage of mail-filter/spamassassin for spam protection

amavisd-new

courier Add courier support
dkim Add DomainKeys Identified Mail support
qmail Add qmail support
razor Add support for mail-filter/razor
spamassassin Add support for mail-filter/spamassassin
zmq Add support for zeromq sockets

ask

procmail Adds support for mail-filter/procmail

assp

spf Adds support for Sender Policy Framework
srs Adds support for Sender Rewriting Scheme

bogofilter

tokyocabinet Enable Tokyo Cabinet database support

clamassassin

clamd Use the app-antivirus/clamav daemon for virus checking
subject-rewrite Adds support for subject rewriting

dcc

rrdtool Enable net-analyzer/rrdtool interface scripts

dspam

daemon Enable support for DSPAM to run in --daemon mode
debug Enable debugging support (don't enable this unless something needs testing!)
domain-scale Build for domain scale setups - puts data to $HOME/data/domain.com/user
hash Enable support for the file-orientated hash driver
large-scale Build for large scale setups - puts data to $HOME/data/u/s/user
small-scale Build for small scale setups - puts data to $HOME/data/user
user-homedirs Build with user homedir support
virtual-users Build with virtual-users support

libmilter

poll Use poll instead of select

maildrop

authlib Add courier-authlib support
tools Install maildirmake and deliverquota tools
trashquota Count deleted messages as part of the maildir quota

mimedefang

poll Use poll instead of select

opendkim

ldap Enable openldap as a dataset facilitator or keys, determining domains to sign for, and any other dataset that opendkim supports.
lmdb Add support for using dev-db/lmdb
lua Enables control over signature verification, filtering and policy to be controlled by user defined lua scripts.
memcached Add support for using dev-libs/libmemcached
opendbx Use opendbx backend to facilitate dataset driven OpenDKIM configuration options like stats, bodylengthdb, etc. against a wide variety of database types
poll Use poll() instead of select() for the provided asynchronous resolver library.
sasl Used to authenticate to a LDAP server in various ways if required.
unbound Use the unbound dnssec library to perform DKIM DNS queries.

opendmarc

spf Use the mail-filter/libspf2 for Sender Policy Framework checking

opensmtpd-extras

filter-clamav filter for scanning with app-antivirus/clamav
filter-dkim-signer filter for adding DKIM signatures to outgoing messages
filter-dnsbl filter for checking hosts against the DNS black lists
filter-lua filter for interfacing with dev-lang/lua
filter-monkey filter for arbitrarily rejecting random emails
filter-pause filter to pause on new connections
filter-perl filter for interfacing with dev-lang/perl
filter-python filter for interfacing with dev-lang/python
filter-regex filter for regular expression matching
filter-spamassassin filter for scanning with mail-filter/spamassassin
filter-stub stub filter
filter-trace trace filter
filter-void void filter
luajit Use JIT for Lua via dev-lang/luajit instead of dev-lang/lua
queue-null null queue
queue-python queue for interfacing with dev-lang/python
queue-ram ram queue
queue-stub stub queue
scheduler-python schedulre for interfacing with python
scheduler-ram ram scheduler
scheduler-stub stub scheduler
table-ldap table for lookups with net-nds/openldap
table-mysql table for lookups with virtual/mysql
table-passwd table for lookups using /etc/passwd
table-postgres table for lookups with dev-db/postgresql
table-python table for interfacing with dev-lang/python
table-redis table for lookups with dev-db/redis
table-socketmap table for lookups using a socket map
table-sqlite table for lookups with dev-db/sqlite3
table-stub stub table

postfwd

tools Install additional tools for testing postfwd

postgrey

targrey Enables the targrey patch

qmail-scanner

spamassassin Build faster mail-filter/spamassassin checks into qmail-scanner

spamassassin

bayes Require a database (MySQL, SQLite, Postgres, or BerkDB) backend to enable the Bayesian filtering database.
qmail Build qmail functionality and docs

spamdyke

tls Enables TLS protocol for spamdyke

zdkimfilter

debug Log process and signal information. Also leave the child process running for gdb examination.
opendbx An alternate statistics based storage engine.

mail-mta

courier

fax Enables fax support in the courier mail server
norewrite Prevents courier mail server from mangling virtual user addresses when sending
web Enable the web interface
webmail Enable the webmail interface

exim

dcc Adds support for Distributed Checksum Clearinghouse (DCC)
dkim Adds support for DomainKeys Identified Mail (DKIM)
dlfunc Install local_scan.h header to compile separate dlfunc libraries
dmarc Adds support for DMARC
dnsdb Adds support for a DNS search for a record whose domain name is the supplied query
dovecot-sasl Adds support for Dovecot's authentication
dsn Adds support for Delivery Status Notifications (DSN)
exiscan-acl Patch providing support for content scanning
lmtp Adds support for lmtp
mbx Adds support for UW's mbx format
pkcs11 Require pkcs11 support in net-libs/gnutls with USE=gnutls
prdr Adds support for Per-Recipient Data Response
proxy Add support for being behind a proxy, such as HAProxy
redis Adds support for querying dev-db/redis
spf Adds support for Sender Policy Framework
srs Adds support for Sender Rewriting Scheme
tpda Adds support for Transport Post-Delivery Actions

msmtp

libsecret Enable libsecret support to store login credentials
mta Enable this to install as system-wide MTA

netqmail

authcram Enable AUTHCRAM support
gencertdaily Generate SSL certificates daily instead of hourly
highvolume Prepare netqmail for high volume servers

opensmtpd

mta Enable this to install as system-wide MTA

postfix

dovecot-sasl Enable net-mail/dovecot protocol version 1 (server only) SASL implementation
eai Add support for SMTPUTF8
ldap-bind Add support for binding to LDAP backend using dev-libs/cyrus-sasl
lmdb Add support for using dev-db/lmdb for lookup tables
memcached Add support for using net-misc/memcached for lookup tables
vda Add support for virtual delivery agent quota enforcing

qmail-ldap

cluster Enable this if you want to have cluster support in qmail-ldap
gencertdaily Generate SSL certificates daily instead of hourly
highvolume Prepare qmail for high volume servers
rfc2307 Add support for RFC2307 compliant uid/gid attributes
rfc822 Add support for RFC822 compliant mail attributes

qpsmtpd

postfix create user with permissions for proper postfix interaction

ssmtp

mta Install symlinks for sendmail-compatible MTA.

mate-base

caja

mate Install x11-themes/mate-icon-theme which is needed when this package is used in the MATE desktop environment.
unique Enable single instance support using dev-libs/libunique.

mate

base Install base MATE Desktop applications that are recommended for the most common usage; for example, this installs the file manager. Disable this and other USE flags if you want a more minimal MATE Desktop.
extras Install additional MATE Desktop applications that are recommended for extended usage of the MATE Desktop as upstream sees it; for example, this installs MATE Desktop's office related applications. Disable this if you plan to use your own non-MATE Desktop alternatives or a custom mixture of MATE and non-MATE packages.
themes Install MATE Desktop's themes; if you use other themes, you can disable this to spare some space and time.

mate-extra

caja-extensions

gajim Add an extension to support net-im/gajim.
image-converter Add image conversion support.
mail Add an extension to support e-mail functionality.
open-terminal Add an extension to support an open terminal.
pidgin Add an extension to support net-im/pidgin
share Add an extension to support sharing files.

mate-media

twolame Bring in twolame gstreamer support

mate-power-manager

applet Enable building of the MATE applet.
man Build power manager's man page.
unique Enable single instance support using dev-libs/libunique.

mate-screensaver

consolekit Enable support for sys-auth/consolkekit

mate-utils

applet Enable the mate dictionary applet

media-fonts

corefonts

tahoma Also install the Tahoma font. Due to the lack of a free bold variant, this may render badly. See bug 184790.

culmus

ancient Install ancient semitic scripts
fancy Install fancy fonts
fontforge Use media-gfx/fontforge to build fonts from source
taamey Install taamey fonts

dejavu

fontforge Use media-gfx/fontforge to build fonts from source

infinality-ultimate-meta

free Install fonts for the "free" preset
latin Install additional latin fonts
minimal Install a minimal set of fonts
ms Install (free) fonts for the "ms" preset

intlfonts

bdf Installs BDF fonts in addition to PCF

liberation-fonts

fontforge Use media-gfx/fontforge to build fonts from source

montecarlo

bdf Install BDF fonts in addition to PCF

mplus-outline-fonts

ipafont Generates new fonts merged with media-fonts/ja-ipafonts

sil-charis

compact Use more compactly spaced font

sil-gentium

compact Also install more compact version of the font.

terminus-font

a-like-o Changes view of letter 'a' - a looks like o (see homepage)
center-tilde Place the '~' character vertically centered on the line instead of to the top.
distinct-l ll2 variant with more distinctive l (lowercase L)
pcf Install Portable Compiled Font (PCF) (required for X11)
pcf-unicode-only Remove non-unicode PCF fonts that could be problematic. See bug #520222.
psf Install PC Screen Font (PSF) with unicode data (for linux console)
quote Changes view of quotes: symmetric ` and ' instead of asymmetric one (see homepage)
raw-font-data Install RAW font data which should be compatible with most UNIX systems (you don't need this on linux)
ru-dv Changes view of Russian letters 'de' and 've' (see homepage)
ru-g Changes view of Russian letter 'ge' (see homepage)
ru-i Changes view of Russian letter 'i' - not like Latin u, but like "mirrored" N (see homepage)
ru-k Changes view of Russian letter 'k' (see homepage)

unifont

fontforge Use media-gfx/fontforge to build fonts from source
utils Install unifont utilities

media-gfx

album

plugins Install optional plugins
themes Install optional themes

asymptote

boehm-gc Enables using the Boehm-Demers-Weiser conservative garbage collector
offscreen Enables off-screen rendering
sigsegv Enables using dev-libs/libsigsegv

blender

boost Enable features depending on boost.
bullet Enable Bullet (Physics Engine).
collada Add support for Collada interchange format through media-libs/opencollada.
colorio Enable OpenColorIO color management.
cycles Build cycles renderer (requires media-libs/openimageio and dev-libs/boost).
dds Adds DDS textures support to Blender.
doc Build C and Python API documentation directly from the source code.
elbeem Adds surface fluid simulation to Blender using El'Beem library.
game-engine Adds Game Engine support to Blender.
ndof Enable NDOF input devices (SpaceNavigator and friends).
openimageio Enable OpenImageIO Support
opennl Enable use of Open Numerical Library
player Build the Blender Player. THis requires the Game engine.
redcode This flag add support for RED CODE camera digital format (5K HD images *.r3d) - EXPERIMENTAL.

brlcad

benchmarks Run benchmarks during test phase (need test option enabled)

comix

rar Pulls app-arch/unrar for rar file support

darktable

colord Support color management using x11-misc/colord
flickr Add support for uploading photos to flickr
geo Enable geotagging support
graphicsmagick Use media-gfx/graphicsmagick for image importing
libsecret Enable libsecret support to store login credentials
opencl Enable opencl support
pax_kernel Triggers paxmarking of main darktable binary
rawspeed Enable the rawspeed backend
slideshow Build the opengl slideshow viewer
squish Enable thumbnail compression via libsquish
web-services Add support for uploading photos to facebook and picasa
webp Enable WebP export support

digikam

addressbook Add support for kdepim
linguas_ha Hausa translation
linguas_mi Maori translation
linguas_ven Venda translation
nepomuk Enable Nepomuk based semantic desktop support (deprecated)
themedesigner Build the digikam theme designer
thumbnails Enable thumbnails database support
video Pull in mplayerthumbs to enable video thumbnails

enblend

gpu GPU support for Enblend
image-cache allow for processing of large images

eog-plugins

flickr Enable uploading to Flickr
map Enable world map display using media-libs/libchamplain
picasa Enable uploading to Google's Picasa Web Albums

exact-image

swig Adds Swig support dev-lang/swig

exiv2

contrib Build additional contrib components

fbida

X Install the Motif based image viewer "ida"
fbcon Install the framebuffer image viewer "fbi"
webp Enable support for the WebP image format

fim

dia Enable DIA file support via app-office/dia
graphicsmagick Enable GraphicsMagick library support
imagemagick Use convert from media-gfx/imagemagick as fallback file opener
xfig Enable FIG file support via media-gfx/xfig

fontforge

cjk Controls whether fontforge understands the gb12345 encoding and installs cidmap package to edit CID-keyed fonts
pango Enable pango font rendering
pasteafter Controls whether fontforge has a paste after command (Useful for making words?). This is kind of fun, but it isn't useful for normal fonts.
tilepath Controls whether fontforge has a tile path command (a variant of expand stroke) This is useful for very decorative fonts, most people won't want it.
truetype-debugger Enable truetype debugger in fontforge
type3 Build in support for type3/svg fonts containing multilayered drawing with strokes, fills, images, etc. Type3 fonts are only supported by postscript printers (not by most windowing displays). They are capable of more exotic images than normal fonts but require much more effort to support.

fotowall

webcam Enable webcam support

freewrl

glew Enable glew extensions
java Build and install java EAI/SAI support library
libeai Build EAI C library
opencl Enable OpenCL support
osc Allows for OSC-based control and communication between multiple freewrl instances

gimp

smp Enable support for multiprocessors

gmic

graphicsmagick Enable support for many common image file formats using the GraphicsMagick++ library
opencv Enable support for webcams using the OpenCV library

graphicsmagick

fpx Enable FlashPix support with media-libs/libfpx
modules Compile graphicsmagick with dynamically loadable modules
q16 Set storage quantum size to 16 (~2*memory)
q32 Set storage quantum size to 32 (~5*memory)
webp Enable support for webp image format

graphviz

X Builds lefty front-end, builds plugin -Txlib, and enables support for x11 in various other modules (needs cairo)
devil Enables DevIL output plugin -Tdevil
gdk-pixbuf Enables gdk-pixbuf2 plugin
gtk Enables gtk+ output plugin -Tgtk (needs cairo)
gts Enables support for gts
lasi Enables PostScript output via media-libs/lasi, for plugin -Tlasi (needs cairo)
qt4 Builds gvedit front-end

gthumb

http Enable webservice integration through net-libs/libsoup
json Compile code that uses the libjson-glib library
libsecret Enable libsecret support to store login credentials
slideshow Enable slideshow plugin
webp Enable support for webp image format

hugin

sift automatically align images with media-gfx/autopano-sift or media-gfx/autopano-sift-C

imagemagick

autotrace Use media-gfx/autotrace to convert bitmaps into vector graphics
corefonts Use media-fonts/corefonts which is required by some commands
fpx Enable media-libs/libfpx support
hdri enable High Dynamic Range Images formats
lqr Enable experimental liquid rescale support using media-libs/liblqr
opencl Enable OpenCL support
pango Enable Pango support using x11-libs/pango
q32 Set quantum depth value to 32
q64 Set quantum depth value to 64
q8 Set quantum depth value to 8
webp Enable webp image format support using media-libs/libwebp

imageworsener

webp enable webp image format support

inkscape

cdr Enable support for CorelDRAW Diagrams
dia pull in app-office/dia for dia import extension
inkjar Enable support for OpenOffice.org SVG jar files
visio Enable support for Microsoft Visio Diagrams
wpg Enable support for WordPerfect Graphics

iscan-plugin-gt-f500

minimal Install the firmware only, and not the plugin.

jpeg2ps

metric Default to A4 paper size

k3d

3ds Enable support for 3D Studio models
cuda Use nvidia cuda toolkit for speeding up computations
gts Add Support for the GNU Triangulated Surface Library sci-libs/gts

kphotoalbum

face Enable face detection and recognition using media-libs/libkface
geolocation Add support for kde-apps/marble
kipi Support for the KDE Image Plugin Interface
map Enable map display support using media-libs/libkgeomap

librecad

tools Build additional tool programs

luminance-hdr

fits Enable support for the FITS format

nip2

goffice use x11-libs/goffice to show plots

nomacs

opencv Build support for media-libs/opencv
webp Build support for WEBP image format
zip Build support for zip archives

nvidia-texture-tools

cg Enable NVIDIA C graphics compiler toolkit plug-in
cuda Enable NVIDIA CUDA toolkit support
glew Enable support for The OpenGL Extension Wrangler Library (media-libs/glew)

openclipart

gzip Compresses clip art using gzip

openexr_viewers

cg Add support for nvidia's cg shaders

photoqt

exiv2 Use media-gfx/exiv2 as optional dependency
graphicsmagick Use media-gfx/graphicsmagick as optional dependency

pngcrush

system-libs Use libpng and libz provided by system

potrace

metric default to a4 paper size and metric measurement

povray

io-restrictions POV-Ray's mechanism for control of I/O operations
mkl Enable support for Intel Vector Math Library, part of sci-libs/mkl

pstoedit

emf Enable media-libs/libemf support
flash Enable media-libs/ming SWF support
pptx Enable support for generating PowerPoint pptx files

qiv

magic Use libmagic to determine mimetypes

qiviewer

webp Build support for WEBP image format

splashutils

fbcondecor Support for the fbcondecor kernel patch.

ufraw

contrast enable contrast setting option
fits Enable support for the FITS image format through sci-libs/cfitsio
timezone enable DST correction for file timestamps

xpaint

pgf Support for loading PGF images

xsane

ocr Enable support for Optical Character Recognition reader

yafaray

blender install media-gfx/blender scripts

media-libs

a52dec

djbfft Prefer D.J. Bernstein's library for fourier transforms

allegro

dumb Enable media-libs/dumb module library support
physfs Enable physfs support
vga Enables the VGA graphics driver

alsa-lib

alisp Enable support for ALISP (ALSA LISP) interpreter for advanced features.

alure

dumb Enable media-libs/dumb module library support
fluidsynth Enables Fluidsynth MIDI software synthesis

assimp

boost Build assimp with boost support
samples Build viewer library
tools Build assimp tool binary

aubio

double-precision Compile in double precision mode.

avidemux-core

aften Enable A/52 (AC-3) audio encoder support.
amr Enable Adaptive Multi-Rate format support via media-libs/opencore-amr.
system-ffmpeg Use the ffmpeg provided by the system.

avidemux-plugins

aften Enable A/52 (AC-3) audio encoder support.
amr Enable Adaptive Multi-Rate format support via media-libs/opencore-amr.
faac Enable free MPEG-4 audio codecs support via media-libs/faac.
faad Enable AAC audio decoding library support via media-libs/faad2.
fribidi Enable unicode bidirectional algorithm support via dev-libs/fribidi.
twolame Enable TwoLAME support via media-sound/twolame, an optimised MPEG Audio Layer 2 (MP2) encoder.
vpx Enable WebM VP8 Codec SDK support via media-libs/libvpx.

cal3d

16bit-indices Enables use of 16bit indices

chromaprint

tools Build and install fpcalc and fpcollect tools

clutter

egl Enable EGL backend.
gtk Use gdk-pixbuf from x11-libs/gtk+ as image rendering backend

cogl

gles2 Enable OpenGL ES 2.0 support
kms Enable KMS support.
pango Build cogl-pango library for x11-libs/pango integration

coin

simage Texture loading via media-libs/simage library

devil

allegro Add support for Allegro
nvtt Add support for dev-util/nvidia-texture-tools

edje

cache Enable caching

elementary

quicklaunch Enable quick-launch support

emotion

vlc Enable support for the media-video/vlc player backend

esdl

image Enable image support

ethumb

emotion Add support for media-libs/emotion

evas

bmp Support windows bitmap (bmp) image loader
eet Support dev-libs/eet
gles Enable gles flavor of gl instead of standard
ico Support windows icon (ico) image loader
ppm Support PPM image loader
psd Support PSD image loader
tga Support tga image loader
wayland Add support for dev-libs/wayland

faad2

digitalradio Digital Radio Mondiale (warning: disables other decoders)

flickcurl

raptor Use media-libs/raptor for proper RDF serializing

fontconfig-infinality

nyx Additional style using croscorefonts

freetype

adobe-cff Use Adobe CFF as default font-renderer
auto-hinter Use the unpatented auto-hinter instead of the (recommended) TrueType bytecode interpreter
bzip2 Support bzip2 compressed PCF fonts.
fontforge Install internal headers required for TrueType debugger in media-gfx/fontforge (built with USE=truetype-debugger)
harfbuzz Use media-libs/harfbuzz for auto-hinting OpenType fonts. WARNING: may trigger circular dependencies!
infinality Enable infinality options for improved LCD filtering
utils Install utilities and examples from ft2demos

freeverb3

audacious Build Audacious plugin
forcefpu Disable assembly code
plugdouble Build plugins in double precision mode (default is float)

ganv

fdgl Use experimental force-directed graph layout

gd

webp Enable support for the webp format

gegl

introspection Use dev-libs/gobject-introspection for introspection.
lensfun Enable support for media-libs/lensfun.
umfpack Enable sparse solving via sci-libs/umfpack.
vala Enable bindings for dev-lang/vala
webp Enable support for media-libs/libwebp

giflib

rle Build converters for RLE format (utah raster toolkit)

glfw

egl Use EGL instead of GLX for GL context creation

gmtk

dconf Enable support for gnome-base/dconf

grilo

network Enable network access for media discovery using net-libs/libsoup
playlist Enable support for playlists through dev-libs/totem-pl-parser
vala Generate bindings for dev-lang/vala

gst-plugins-bad

egl Enable EGL support
gles2 Enable GLES2 support

gst-plugins-base

ivorbis Enable integer based vorbis decoder.
pango Enable pango GStreamer plugin

gstreamer

orc Disable some PaX memory protections to allow plugins that use dev-lang/orc for runtime optimization to be used on hardened PaX systems

harfbuzz

glib Compile with GLib Unicode support
graphite Use graphite to render complex non-Roman writing systems

jbig2enc

webp Add support for WEBP image format

leptonica

utils Install command-line utilities
webp Adds support for the WebP image format

libass

enca Enables support for charset discovery and conversion.
harfbuzz Enables OpenType shaping via media-libs/harfbuzz.

libbdplus

aacs Add support for decryption of AACS

libbluray

aacs Add support for decryption of AACS
bdplus Use media-libs/libbdplus for BD+ decryption
java Add support for BD-J
utils Install command-line utilities and examples

libcanberra

alsa Enables ALSA sound driver.
gstreamer Enables gstreamer sound driver. Not useful when alsa or pulseaudio is available.
gtk Enables building of gtk+ helper library, gtk+ runtime sound effects and the canberra-gtk-play utility. To enable the gtk+ sound effects add canberra-gtk-module to the colon separated list of modules in the GTK_MODULES environment variable.
gtk3 Enables building of gtk+3 helper library, gtk+3 runtime sound effects and the canberra-gtk-play utility. To enable the gtk+3 sound effects add canberra-gtk-module to the colon separated list of modules in the GTK_MODULES environment variable.
pulseaudio Enables PulseAudio sound driver that should be able to support positional event sounds. This is the preferred choice for best sound events experience and picked by default if compiled in and possible to use at runtime.
sound Install x11-themes/sound-theme-freedesktop to get sounds on Gnome and Xfce.
tdb Enables Trivial Database support for caching purposes.

libde265

tools Install addtional tools, require USE=qt4 or qt5

libextractor

archive Enable archive support using app-arch/libarchive
gsf Enable OLE2 (MS Office) plug-in support using gnome-base/libgsf
magic Enable magic support using sys-apps/file
midi Enable MIDI support through media-libs/libsmf

libggi

vis Enables sparc vis support for libggi

libgphoto2

serial Enable serial port support

libgpod

gtk Enable ArtworkDB support

liblastfm

fingerprint Build the lastfm-fingerprint library

libmp4v2

utils Install command-line utilities

libomxil-bellagio

audioeffects enable audio volume/mixer effects components
clocksrc enable clock component
videoscheduler enable xvideosink video scheduler

libpagemaker

tools Build build tools

libpng

apng support unofficial APNG (Animated PNG) spec

libpostproc

pic Force shared libraries to be built as PIC (this is slower).

libquicktime

schroedinger Enable Dirac video support (an advanced royalty-free video compression format) via libschroedinger (high-speed implementation in C of the Dirac codec)

libraw

demosaic Enable support for external interpolation algorithms

libsdl

joystick Control joystick support (disable at your own risk)
sound Control audio support (disable at your own risk)
tslib Build with tslib support for touchscreen devices
video Control video support (disable at your own risk)

libsdl2

fusionsound use FusionSound audio driver
gles include OpenGL ES support
haptic Enable the haptic (force feedback) subsystem
joystick Control joystick support (disable at your own risk)
sound Control audio support (disable at your own risk)
tslib Build with tslib support for touchscreen devices
video Control video support (disable at your own risk)

libvisio

tools Build conversion tools

libvpx

postproc Enable additional post processing filters

libwebp

experimental Build with -DWEBP_EXPERIMENTAL_FEATURES
swap-16bit-csp Enable byte swapping for 16 bit colorspace

lilv

dyn-manifest Add LV2 Dynamic Manifest support. See http://lv2plug.in/ns/ext/dynmanifest/

lv2

plugins Enables examples plugins.

lvtk

gtk2 Enable x11-libs/gtk+:2 based GUI support
tools Compile and install ttl2c tool

mash

introspection Use dev-libs/gobject-introspection for introspection

mediastreamer

amr Use of AMR Narrow Band codec plugin
filters Enable compilation of filters
g726 Support g726 codec
g729 Use g726 codec plugin
ilbc Use of iLBC (RFC3951) codec plugin
ntp-timestamp Turn on NTP timestamping on received packet
opus Enable opus codec support
ortp Enable usage of net-libs/ortp
pcap Enable usage of net-libs/libpcap
silk Use silk (skype protocol) codec plugin
video Enable video support

memphis

introspection Use dev-libs/gobject-introspection for introspection
vala Add support for Vala

mesa

bindist Disable patent-encumbered ARB_texture_float, EXT_texture_shared_exponent, and EXT_packed_float extensions.
classic Build drivers based on the classic architecture.
d3d9 Enable Direct 3D9 API through Nine state tracker. Can be used together with patched wine.
dri3 Enable DRI3 support.
egl Enable EGL support.
gallium Build drivers based on Gallium3D, the new architecture for 3D graphics drivers.
gbm Enable the Graphics Buffer Manager for EGL on KMS.
gles Enable GLES (both v1 and v2) support.
gles1 Enable GLESv1 support.
gles2 Enable GLESv2 support.
llvm Enable LLVM backend for Gallium3D.
opencl Enable the Clover Gallium OpenCL state tracker.
openmax Enable OpenMAX video decode/encode acceleration for Gallium3D.
openvg Enable the OpenVG 2D acceleration API for Gallium3D.
osmesa Build the Mesa library for off-screen rendering.
pax_kernel Enable if the user plans to run the package under a pax enabled hardened kernel
pic disable optimized assembly code that is not PIC friendly
vdpau Enable the VDPAU acceleration interface for the Gallium3D Video Layer.
wayland Enable support for dev-libs/wayland
xa Enable the XA (X Acceleration) API for Gallium3D.
xvmc Enable the XvMC acceleration interface for the Gallium3D Video Layer.

mlt

compressed-lumas Compress the luma files in png.
frei0r Build the module for media-plugins/frei0r-plugins
kdenlive Build support for media-video/kdenlive
lua Build SWIG bindings for Lua
melt Build the melt commandline tool
python Build SWIG bindings for Python
rtaudio Builds rtaudio consumer for native audio support on multiple platforms.
ruby Build SWIG bindings for Ruby

netpbm

rle Build converters for the RLE format (utah raster toolkit)

openal

alstream Build and install the FFmpeg based alstream example utility

opencolorio

pdf Install extra documentation in PDF format

opencv

cuda Enable NVIDIA Cuda computations support
eigen Enable usage of dev-cpp/eigen for computations
ipp Enable Intel Integrated Primitive support
opencl Add support for OpenCL
testprograms Build and install programs for testing OpenCV (performance)
vtk Build new 3D visualization module viz based on sci-libs/vtk

openh264

plugin Install the Gecko Media Plugin (GMP) for use with Mozilla packages
utils Install the CLI encoder and decoder utilities

openimageio

colorio Use media-gfx/opencolorio
opencv Use media-libs/opencv
tbb Use dev-cpp/tbb

opus

custom-modes Build with custom-modes.

opusfile

fixed-point Enable fixed-point arithmetic operations
float Enable floating point arithmetic operations
http Enable http connections

phonon

designer Install plugin for dev-qt/designer
vlc Install VLC Phonon backend
zeitgeist Add support for Zeitgeist event tracking system

phonon-gstreamer

network Enable network streaming support via libsoup

portmidi

test-programs Install various example programs

quvi

json Enable support for JSON output

raptor

json Enable support for JSON parsing

sdif

ftruncate Enables usage of ftruncate v. truncate

sdl-image

webp support loading WEBP images

sdl-mixer

fluidsynth Use media-sound/fluidsynth for MIDI support
midi basic support for MIDI files
mod basic support for MOD files
playtools Install playwave and playmus tools (useful for testing)
smpeg Use media-libs/smpeg for MP3 support
wav support WAVE files

sdl-sound

physfs Enable physfs support

sdl2-image

webp support loading WEBP images

sdl2-mixer

fluidsynth Use media-sound/fluidsynth for MIDI support
midi basic support for MIDI files
mod basic support for MOD files
playtools Install playwave and playmus tools (useful for testing)
smpeg Use media-libs/smpeg for MP3 support
tremor enable OGG Vorbis music via libtremor
wav support WAVE files

sge

image enable sdl-image support

silgraphite

pango Enables the pango-graphite pango module.

spandsp

fixed-point Enable fixed point support

svgalib

kernel-helper Build the helper kernel module

taglib

asf Provide support for Microsoft's 'advanced systems format' media container.

tremor

low-accuracy enable 32bit only multiply operations

vips

fits Enable support for the FITS image format through sci-libs/cfitsio

waffle

egl Enable EGL support
gbm Enable support for the Generic Buffer Manager (gbm)
wayland Enable Wayland support

x264

10bit Set output bit depth to 10, this may not be compatible with all decoders
interlaced enable interlaced encoding support, this can decrease encoding speed by up to 2%
opencl Add support for OpenCL.
pic disable optimized assembly code that is not PIC friendly

x265

10bit Set output bit depth to 10

xine-lib

bluray Enable playback of Blu-ray filesystems using media-libs/libbluray
dxr3 Enable support for DXR3 mpeg acceleration cards.
flac Build the media-libs/flac based FLAC demuxer and decoder. This flag is not needed for playing FLAC content, neither standalone nor in Ogg container (OggFLAC), but might have better support for exotic features like 24-bit samples or 96kHz sample rates.
fusion Enable support for the Fusion audio sub system
gtk Build the gdkpixbuf-based image decoder plugin.
imagemagick Build the ImageMagick-based image decoder plugin.
mad Build the media-libs/libmad based mp3 decoder. This mp3 decoder has superior support compared to the one coming from FFmpeg that is used as a fallback. If you experience any bad behaviour with mp3 files (skipping, distorted sound) make sure you enabled this USE flag.
mmap Use mmap() function while reading file from local disks. Using mmap() will use more virtual memory space, but leaves to the Kernel the task of caching the file's data. mmap() access should be faster, but might misbehave if the device where the file resides in is removed during playback.
truetype Use media-libs/freetype for font rendering and media-libs/fontconfig for font discovery. Enabling this USE flag will allow OSD (such as subtitles) to use more advanced font and to more easily select which font to use. The support for TrueType fonts in xine-lib is still experimental, and might not be as good looking as the bitmap fonts used with this USE flag disabled.
vdr Build the VDR plugin
vidix Enable support for vidix video output.
vis Adds support for SIMD optimizations for UltraSPARC processors.
vpx Enable VP8 codec support via media-libs/libvpx.
xvmc Enable support for XVideo Motion Compensation (accelerated mpeg playback).

xvid

pic disable optimized assembly code that is not PIC friendly

media-plugins

audacious-plugins

adplug Build with AdPlug (Adlib sound card emulation) support
bs2b Enable Bauer Bauer stereophonic-to-binaural headphone filter
cue Support CUE sheets using the libcue library
fluidsynth Support FluidSynth as MIDI synth backend
gtk3 Link against version 3 of the GIMP Toolkit instead of version 2 (x11-libs/gtk+)
midi Build with amidi-plug (MIDI synth) support
scrobbler Build with scrobbler/LastFM submission support
sid Build with SID (Commodore 64 Audio) support

banshee-community-extensions

lastfmfingerprint Enable support to ientify your music automatically, using the Last.fm online service.
lirc Enable the remote control plugin (uses app-misc/lirc)
lyrics Enable support for automatically fetching lyrics
mirage Enable the Mirage plugin which automatically, and intelligently generates playlists for you
telepathy Enables the Telepathy plugin which lets you to share and stream music with IM buddies
zeitgeist Build the plugin to inject events to gnome-extra/zeitgeist

calf

lv2 Add support for Ladspa V2

frei0r-plugins

facedetect Enables building of facedetect plugin, which depends on media-libs/opencv
scale0tilt Enables building of scale0tilt and vectorscope plugins, which depend on media-libs/gavl

gkrellmpc

threads Use separate thread to init connection (unsafe)

grilo-plugins

daap Enable dmap support through net-libs/libdmapsharing
flickr Enable Flickr support
freebox Build support for viewing TV channels using Freebox
gnome-online-accounts Enable net-libs/gnome-online-accounts support
pocket Support for showing content from Pocket
subtitles Enables support for subtitle from OpenSubtitles
thetvdb Build support for thetvdb.com
tracker Build support for content discovery using the app-misc/tracker indexer
vimeo Build support for Vimeo content discovery using net-libs/libsoup and dev-libs/libgcrypt
youtube Build support for YouTube content discovery using dev-libs/libgdata

gst-plugins-gl

libvisual Enable visualization effects via media-libs/libvisual

gst-plugins-meta

http Enable http streaming via net-libs/libsoup
libvisual Enable visualization effects via media-libs/libvisual
opus Enable Opus audio codec support
vpx Enables vp8 codec support using libvpx, required to play some HTML5 videos

kipi-plugins

expoblending Build the expoblending plugin, which requires media-gfx/hugin
gpssync Build the gpssync plugin, which requires media-lib/libkgeomap and thereby marble
linguas_ha Hausa translation
linguas_mi Maori translation
linguas_tt ?? translation
linguas_ven Venda translation
mediawiki Build the mediawiki export plugin
panorama Pull in dependencies needed by panorama plugin
redeyes Add redeyes removal support
videoslideshow Build videoslideshow plugin
vkontakte Build plugin for vkontakte.ru

mediastreamer-ilbc

20ms-frames enable 20ms frame size (default is 30ms). Some VOIP providers such as Gizmo5 (aka Sipphone) require the codec to be compiled with the 30ms setting.

mythplugins

cdr Allows MythMusic to burn CD-Rs
exif Allows MythGallery to read EXIF data from photos
fftw Adds visual effects to MythMusic when playing back music
hls HTTP Live Streaming support
mytharchive Allows you to archive recorded content to CD or DVD
mythbrowser Adds a web browser within MythTV
mythgallery Adds a picture viewing gallery within MythTV
mythgame Adds a frontend to various ROM emulators within MythTV
mythmusic Adds the ability for MythTV to act as a music player
mythnetvision Adds the ability to view netvision devices within MythTV
mythnews Adds a news viewer within MythTV
mythweather Adds weather information within MythTV
mythzoneminder Adds support for zoneminder (requires a server with the appropriate mythtv daemon somewhere on the network).
raw Allows MythGallery to view photos saved in RAW format

vdr-burn

dvdarchive DMH DVD - Archive

vdr-epgsearch

conflictcheckonly ToDo
epgsearchonly ToDo
quicksearch ToDo
tre Add support for unlimited fuzzy searching with help of dev-libs/tre library

vdr-graphtft

graphtft-fe Install external x11 remote frontend
theme_avp graphTFT Alien vs. Predato theme
theme_deepblue graphTFT default theme
theme_deeppurple graphTFT Deep Purple theme
theme_poetter graphTFT Poetter theme
touchscreen Enable Touchscreen support

vdr-music

graphtft Enable support for media-plugins/vdr-graphtft

vdr-pvr350

yaepg Enables full support for the output format of media-plugins/vdr-yaepg

vdr-streamdev

client Compile the VDR plugin vdr-streamdev-client that acts like a dvb-budget card
server Compile the VDR plugin vdr-streamdev-server that allows remote systems to access the DVB cards used for the local VDR

vdr-text2skin

contrib Install user contributed scripts

vdr-vdrmanager

stream Add support for streaming Video to Android client

vdr-weatherng

dxr3 enables lower osd color depth for dxr3 cards

vdr-xine

yaepg Enables support for the plugin vdr-yaepg (showing scaled video besides OSD)

vdr-xineliboutput

bluray Enable BluRay metadata support through media-libs/libbluray
cec Enable CEC support through dev-libs/libcec
libextractor Use media-libs/libextract to gather files' metadata in media-player
vdr Compile the vdr output plugin to use local or remote xine as output
xine Compile the xine input plugin for displaying vdr video and OSD

media-radio

ax25-tools

X Enable some X based configuration tools.

fldigi

hamlib Enables support by the Hamlib amateur radio rig control library to get/set frequency and mode of the ham radio in use

tucnak2

ftdi Enable support for FTDI USB chips
hamlib Enables support by the Hamlib amateur radio rig control library to get/set frequency and mode of the ham radio

unixcw

ncurses Enables building the curses based morse code tutor program 'cwcp'.

xastir

festival Enable text to speech synthesizer
gdal Support for some further map formats
geotiff Install geotiff support. Allows using USGS DRG topo maps or other types of geotiff mapes/images
graphicsmagick Use graphicsmagick instead imagemagick for rendering

media-sound

abcde

id3tag Support ID3, ID3v2 tagging of audio files
mac Enable support for Monkey's Audio files
normalize Add support for normalizing audio file volume levels
opus Support opus encoding using opusenc
replaygain Support for Replay Gain metadata, for relative volume adjustment

abcm2ps

pango Use the pango library to render fonts with non-latin characters

alsa-utils

libsamplerate install utils that use libsamplerate (e.g. alsaloop)
ncurses install utils that use ncurses (e.g. alsamixer)

alsaplayer

id3tag Enables ID3 tagging with id3tag library

amarok

embedded Use libmysqld, MySQL embedded server library. Try disabling this if you encounter -PIC related in amarok, it will make amarok rely only on standalone MySQL server.
lastfm Enable Last.fm streaming services support through media-libs/liblastfm
mp3tunes Enable mp3tunes integration
mtp Enable support for libMTP (Plays4Sure) devices access through libmtp
nepomuk Enable Nepomuk based semantic desktop support (deprecated)
ofa Use media-libs/libofa to compute MusicDNS acoustic fingerprints (used by MusicBrainz)
utils Build the utils - old media-sound/amarok-utils

amsynth

dssi Enable support for DSSI Soft Synth Interface

aqualung

ifp Enable support for iRiver iFP portable audio players
lua Enable support for programmable title formatting with dev-lang/lua
mac Enable support for decoding Monkey's Audio files
podcast Enable podcast support
systray Enable system tray support

ardour

lv2 Add support for Ladspa V2

ario

audioscrobbler Enable song tracking via last.fm
idle Enable experimental support for MPD's idle command to reduce bandwidth and cpu usage, requires MPD 0.14

asunder

mac Support for creation of Monkey's Audio files (APE)
opus Support for creation of Opus files

audacious

chardet Try to handle non-UTF8 chinese/japanese/korean ID3 tags
gtk3 Link against version 3 of the GIMP Toolkit instead of version 2 (x11-libs/gtk+)

audacity

id3tag Enables ID3 tagging with id3tag library
libsoxr Uses media-libs/soxr as audio resampling library: Better quality than the included resampler and much faster than libsamplerate while keeping almost the same quality.
lv2 Add support for Ladspa V2
midi Enables MIDI support
portmixer Enable the internal portmixer feature
sbsms Enables sbsms library support for slower, more accurate pitch and tempo changing
soundtouch Enables soundtouch library support for pitch and tempo changing
twolame Enables twolame support (MPEG Audio Layer 2 encoder)
vamp Enables vamp plugins support (Audio analysing plugins)
vst Enable VST plugin support

banshee

bpm Build beats per minute detection extension
cdda Build with audio CD support
daap Build with Daap support
karma Build with karma support
web Enable support for plugins that access web-based services such as Amazon and wikipedia (requires net-libs/webkit-gtk)
youtube Enable the Youtube plugin

beets

beatport Enable support for beatport.com API
bpd Enable support for media-sound/mpd server emulation
chroma Enable support for acoustic fingerprinting plugin using (media-libs/chromaprint)
convert Enable support for the convert plugin which makes it possible to transcode files
discogs Enable support for the discogs API plugin
echonest Enable support for fetching and storing acoustic attributes of a track from Echo Nest
echonest_tempo Enable support for writing the BPM of a track into its metadata
lastgenre Enable support for importing music genres from last.fm tags
mpdstats Enable support for collecting statistic about listening habits from media-sound/mpd
replaygain Enable support for Replay Gain metadata calculation during import
web Enable embedded webserver support through dev-python/flask

cantata

dynamic Enable support for dynamic playlists
http-server Enable internal HTTP server to play non-MPD files
online-services Enable support for online services (Jamendo, Magnatune, SoundCloud, and Podcasts)
replaygain Enable ReplayGain support, for relative volume adjustments
streams Enable support for streams tab (to save favourite streams, and search for others)

clementine

box Enable Box support
dropbox Enable Dropbox support
googledrive Enable Google Drive support
lastfm Use liblastfm for fetching song info, scrobbling and radio streams
moodbar Enable moodbar support
projectm Build with ProjectM visualization
skydrive Enable Skydrive support
system-sqlite Use the system-wide dev-db/sqlite installation
ubuntu-one Enable Ubuntu One support
wiimote Enable support for Wii remote

cmus

cdio use libcdio for CD support
cue enable CUE sheet parsing
discid enable reading the ID of the inserted CD
opus enable support for media-libs/opusfile
pidgin install support script for net-im/pidgin
tremor use libivorbis from media-libs/tremor instead of media-libs/libvorbis
wma add support for Windows Media Audio

csound

beats Build the beats score frontend
chua Build the chua opcodes
csoundac Build the CsoundAC extension module
double-precision Use double-precision floating point for audio samples
dssi Build the DSSI opcodes
fluidsynth Build the fluidsynth opcodes
image Build the image opcodes
keyboard Build Virtual MIDI keyboard
linear Build the linear algebra Opcodes
luajit Use the lua just-in-time compiler dev-lang/luajit instead of dev-lang/lua
portmidi Build the PortMIDI I/O module
samples Install the HRTF datafiles for use with hrtfmove, hrtfmove2, hrtfstat, hrtfearly, and hrtfreverb
score Build the alternative score parser
stk Build the stk opcodes
tcl Build the tcl interface and clients
utils Build stand-alone executables for utilities that can also be used via `csound -U`

darkice

aacplus AAC+ encoding via media-libs/libaacplus
opus Enable Opus audio codec support
twolame Build with twolame support

denemo

fluidsynth Enable Fluidsynth MIDI software synthesis
portmidi Enable support for the portmidi backend

dir2ogg

mac Add support for decoding Monkey's Audio files
wma Add support for wma files through mplayer

easytag

gtk2 Enable GTK+:2 support and disable default GTK+:3 support
gtk3 Enable GTK+:3 support (default) and disable GTK+:2 support
opus Enable support for media-libs/opus and media-libs/opusfile (opus audio codec)

ecasound

lv2 Add support for Ladspa V2
oil Use dev-libs/liboil for inner loop optimizations

fapg

xspf Enable support for saving XSPF playlists.

flacon

mac Add support for Monkey's Audio files
replaygain Support for Replay Gain metadata, for relative volume adjustment
tta Add support for True Audio encoding

forked-daapd

itunes Enable support for iTunes library XML
lastfm Enable LastFM scrobbling support
mpd Enable streaming to mpd

freewheeling

fluidsynth compile with support for fluidsynth

frescobaldi

portmidi Enable media-libs/portmidi support

gejengel

audioscrobbler Enable track submission on last.fm

gimmix

cover Enable cover art fetching
lyrics Enable lyric fetching

gmpc

unique Enable single instance support using dev-libs/libunique
xspf Enable support for reading and saving XSPF playlists

google-musicmanager

log Enables advanced logging through dev-libs/log4cxx

gpodder

webkit Enable the webkit rendering engine for HTML episode shownotes

herrie

http Enable http streaming
xspf Enable support for reading and saving XSPF playlists

hydrogen

archive Use libarchive instead of libtar

jack-audio-connection-kit

coreaudio Build the CoreAudio driver on Mac OS X systems
cpudetection Enables runtime cpudetection
pam Add basic realime configuration via sys-auth/realtime-base

jalv

gtk2 Adds support for GTK+2 in addition to GTK+3 controlled by the gtk useflag.
gtkmm Adds support for dev-cpp/gtkmm: C++ interface for GTK+2

kid3

acoustid Enable support for acoustic fingerprinting plugin using (media-libs/chromaprint)
phonon Enable sound support via media-libs/phonon or dev-qt/qtphonon

kwave

opus Enable Opus audio codec support
phonon Enable playback via Phonon

lame

mp3rtp Build the mp3-to-RTP streaming utility. **UNSUPPORTED**

lmms

fluidsynth Enables Fluidsynth MIDI software synthesis plugin.
stk Enables STK Mallet plugin.
vst Enables the VeSTige plugin to run VST plugins through Wine.

lyvi

mpris Enable MPRIS support

mangler

espeak Text to speech engine
g15 Logitech g15 lcd support
opus Codec specialized for speech over the internet

mixxx

hid Enable HID controller support
shout Enable broadcasting support via media-libs/libshout
vamp Enable vamp analyzing plugins support

moc

cache Enable tags caching support
magic Use libmagic to determine mimetypes
sid Build with SID (Commodore 64 Audio) support
tremor Build vorbis support using an integer implementation of the vorbis library (media-libs/tremor)

mp3blaster

sid Build with SID (Commodore 64 Audio) support

mp3splt-gtk

audacious Include media-sound/audacious support
gtk3 Link against x11-libs/gtk+:3 instead of x11-libs/gtk+:2

mpd

adplug Enable the AdPlug decoder plugin
cdio Use libcdio for ISO9660 parsing support
curl Support for web stream listening
faad Use external faad library for AAC decoding
fifo Support writing audio to a FIFO
fluidsynth Enables Fluidsynth MIDI software synthesis (discouraged)
glib Enable GLib usage
gme Enables support for media-libs/game-music-emu for playing various video game music formats.
id3tag Support for ID3 tags
inotify Use the Linux kernel inotify subsystem to notice changes to mpd music library
lame Support for MP3 streaming via Icecast2
lastfmradio Support listening to last.fm radio stations
libmpdclient Enable support for remote mpd databases
libsoxr Enable the libsoxr resampler
mpg123 Enable support for mp3 decoding over media-sound/mpg123
network Enables network streaming support
nfs Enable support for the Network File System
opus Enable Opus codec support
pipe Support writing audio to a pipe
recorder Enables output plugin for recording radio streams
sid Build with SID (Commodore 64 Audio) support
soundcloud Build plugin to access soundcloud
soup Use net-libs/libsoup for HTTP streaming
systemd Enable support for systemd socket activation
twolame Support twolame MPEG-2 encoding
wildmidi Enable MIDI support via wildmidi
zip Support for ZIP files

mpfc

wav Enable wav audio codec support

mpg123

int-quality Use rounding instead of fast truncation for integer output, where possible

mumble

g15 Enable support for the Logitech G15 LCD (and compatible devices).
speech Enable text-to-speech support in Mumble.

murmur

ice Use dev-cpp/Ice to enable remote control capabilities.

ncmpc

artist-screen Enable artist screen
chat-screen Enable the chat screen
colors Enable color support
help-screen Enable the help screen
key-screen Enable key editor screen
lyrics-screen Enable lyrics screen
mouse Enable curses getmouse support
search-screen Enable search screen
song-screen Enable song viewer screen

ncmpcpp

clock Enable clock screen
outputs Enable outputs screen
visualizer Enable visualizer screen with sound wave/frequency spectrum modes

patchage

jack-dbus Use Jack via D-Bus instead of libjack
session Include experimental Jack session management (save/restore) support

pianobooster

fluidsynth Enable Fluidsynth MIDI software synthesis

picard

acoustid Use media-libs/chromaprint for acoustic fingerprinting

pithos

appindicator Enable usage of appindicator to export menu options in to unity
keybinder Use keybinder to enable global key bindings

pms

regex Enable regular expression searches using dev-libs/boost

podcatcher

bittorrent Enable support for bittorrent downloads

pragha

glyr Enable music metadata searchengine support using media-libs/glyr
grilo Play songs on DLNA servers using media-libs/grilo
keybinder Enable shortcut support using dev-libs/keybinder
lastfm Enable last.fm support using media-libs/libclastfm
peas Enable various plugins that will pull in dev-libs/libpeas as a dependency
playlist Enable enhanced playlist support using dev-libs/totem-pl-parser
rygel Share music on DLNA using net-misc/rygel
soup Search metadata on AcoustID and radios on TuneIn using net-libs/libsoup

puddletag

acoustid Use media-libs/chromaprint for acoustic fingerprinting
cover Enables editing of FLAC cover art
musicbrainz Enables support for musicbrainz, needs dev-python/python-musicbrainz
quodlibet Enables support for editing media-sound/quodlibet databases

pulseaudio

X Build the X11 publish module to export PulseAudio information through X11 protocol for clients to make use. Don't enable this flag if you want to use a system wide instance. If unsure, enable this flag.
alsa-plugin Request installing media-plugins/alsa-plugins with PulseAudio plugin enabled. This ensures that clients supporting ALSA only will use PulseAudio.
asyncns Use libasyncns for asynchronous name resolution.
doc Build the doxygen-described API documentation.
equalizer Enable the equalizer module (requires sci-libs/fftw).
gdbm Use sys-libs/gdbm to store PulseAudio databases. Recommended for desktop usage. This flag causes the whole package to be licensed under GPL-2 or later.
glib Add support to dev-libs/glib-based mainloop for the libpulse client library, to allow using libpulse on glib-based programs.
gnome Use GConf to store user preferences on streams and so on. Don't enable this flag if you want to use a system wide instance. If unsure, enable this flag.
native-headset Build with native HSP backend for bluez 5.
ofono-headset Build with oFono HFP backend for bluez 5, requires net-misc/ofono.
oss Enable OSS sink/source (output/input). Deprecated, upstream does not support this on systems where other sink/source systems are available (i.e.: Linux). The padsp wrapper is now always build if the system supports OSS at all.
realtime Makes PulseAudio use RealtimeKit (sys-auth/rtkit) to get real-time priority while running.
ssl Use dev-libs/openssl to provide support for RAOP (AirPort) streaming.
system-wide Allow preparation and installation of the system-wide init script for PulseAudio. Since this support is only supported for embedded situations, do not enable without reading the upstream instructions at http://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/WhatIsWrongWithSystemWide/ .
systemd Build with sys-apps/systemd support to replace standalone ConsoleKit.
webrtc-aec Uses the webrtc.org AudioProcessing library for enhancing VoIP calls greatly in applications that support it by performing acoustic echo cancellation, analog gain control, noise suppression and other processing.
xen Builds a special paravirtualized module for running in a Xen guest.

qmmp

bs2b Enable Bauer stereophonic-to-binaural headphone filter
cover Enable album cover support
crossfade Enable crossfade effect when switching tracks
enca Detects the character encoding automatically
game Enable Game music support
kde Use kde4 notifier system
lyrics Fetch track lyrics from the web
midi Enable midi support using wildmidi library
mpris Enable MPRIS support
notifier Enable qmmps' notifier system
opus Enable the opus plugin
projectm Enable projectm music visualization plugin
scrobbler Enable audioscrobbler/last.fm support
stereo Enable stereo effect
tray Build tray icon

qsampler

libgig Enable libgig support for loading Gigasampler files and DLS (Downloadable Sounds) Level 1/2 files

qtractor

dssi Enable support for DSSI Soft Synth Interface
rubberband Enable support for in-place audio clip pitch-shifting through the rubberband library

qtscrobbler

cli Build commandline client

quark

gnome Provides tray-icon and enables gconf support

rezound

16bittmp Use 16bit temporary files (default 32bit float), useful for slower computers
soundtouch compile with support for soundtouch

rhythmbox

daap Build the local network music sharing plugin which uses the DAAP protocol using net-libs/libdmapsharing
html Use net-libs/webkit-gtk for detecting and displaying HTML podcast episode descriptions.
libsecret Enable libsecret support to store login credentials
visualizer Enable support for visualizations using media-plugins/gst-plugins-libvisual
zeitgeist Build the plugin to inject events to gnome-extra/zeitgeist

shntool

alac Add support for Apple Lossless Audio Codec files
mac Add support for Monkey's Audio files

snd

s7 Enable the s7 extension language (a version of Scheme)

sonata

lyrics Support for lyrics fetching
trayicon Enable support for trayicon

sonic-visualiser

id3tag Enables ID3 tagging with id3tag library

soundconverter

opus Enable Opus audio codec support

sox

amr Enables Adaptive Multi-Rate Audio support
id3tag Enables ID3 tagging with id3tag library
opus Enables reading Ogg Opus files.
twolame Enables twolame support (MPEG Audio Layer 2 encoder)

split2flac

enca Try to guess the charset using enca
flake Add support for Flake, alternative FLAC encoder
mac Add support for Monkey's Audio files
replaygain Support for Replay Gain metadata, for relative volume adjustment

spotify

pax_kernel Triggers a paxmarking of the main Spotify binary

squeezeslave

display Enable a text-based display
tremor Use a fixed-point version of the Ogg Vorbis decoder (media-libs/tremor)
wma Enable support for streaming Windows Media Audio
zones Pairs surround sound speakers into stereo zones (requires 5.1 setup or better)

teamspeak-server-bin

tsdns Make use of TeamSpeak DNS.

tomahawk

hatchet Enable support for the synchronisation through Hatchet
telepathy Enable support for the real-time communication framework telepathy

traverso

lv2 Add support for Ladspa V2

umurmur

polarssl Use net-libs/polarssl instead of dev-libs/openssl
shm Enable shared memory support

vimpc

boost Use boost instead of C++11 libraries

vorbis-tools

kate Adds support for Ogg Kate subtitles via libkate.
ogg123 Build ogg123 player, needs libao and curl

wildmidi

player Install the wildmidi player

xmms2

airplay Support for airplay format
asf Support for Monkey's Audio (APE) format with help of bundled libasf
gvfs Transport for glibs virtual filesystem
ices Icecast source output plugin
mac Support for Monkey's Audio (APE) format with help of media-sound/mac
mlib-update Enable building of xmms2-mlib-updater client
ofa Support for Open Fingerprint Architecture (OFA)
phonehome This client sends anonymous usage-statistics to the xmms2
server Build xmms2 player daemon (otherwise only clients are built)
sid Support for C64 SID
vocoder Phase vocoder effect plugin
xml Enable support for various XML based playlists and sources: RSS, XSPF

xmp

audacious Enable audacious support

xnoise

lastfm Enable support for lastfm cover art fetching and scrobbling
lyrics Enable support for lyrics fetching

xwax

alsa Adds support for ALSA audio input/output.
cdda Sets runtime dependencies to support decoding audio from a compact disc.
fallback Sets runtime dependencies to support decoding "other" audio files.
jack Adds support for audio input/output via the JACK Audio Connection Kit.
mp3 Sets runtime dependencies to support decoding MP3 audio.
oss Adds support for OSS (open sound system) audio input/output.

yoshimi

lv2 Add support for Ladspa V2

media-tv

freevo

mixer Enable support for adjusting volume via media-sound/aumix
tv Enable support for the tv guide plugin

gentoo-vdr-scripts

nvram Add support for using nvram-wakeup to set wakeup time in bios

kodi

airplay enable AirPlay support
bluray Enable playback of Blu-ray filesystems
cec Enable support for HDMI-CEC devices via libcec
fishbmc Enable fishBMC visualization plugin
gles Enable support for GLES
goom Enable GOOM visualization plugin
midi Support MIDI files
nfs Enable NFS client support
projectm Enable projectM visualization plugin
pvr Enable MythTV support
rsxs Enable really slick X screensavers
rtmp Enable Real Time Messaging Protocol using librtmp
sftp Support browsing files over SFTP
spectrum Enable spectrum visualization plugin
texturepacker Support packing skin textures
waveform Enable waveform visualization plugin
webserver Enable internal webserver
xrandr Support X randr extension

linuxtv-dvb-apps

alevt Build videotext decoder

me-tv

http Installation of Web-frontend

mythtv

alsa Allows MythTV to directly output sound to ALSA devices, this is needed if you are using ALSA dmix or SPDIF. Note, you will have to physically type your device into the MythTV configuration since it will only give you /dev/dsp devices in the drop down.
altivec Builds ffmpeg's codec libraries with altivec support.
autostart Uses a custom autostart configuration gleaned from experience with MythTV since its early versions and discussed with other MythTV maintainers and users. Does not rely on KDE being installed like most methods do.
bluray Pulls in libbluray for BluRay support.
cec Allows you to control CEC enabled TVs via HDMI. Currently requires a USB based CEC -> HDMI injector between your TV and video card since no graphics drivers support CEC natively.
crystalhd Allows you to utilize a Broadcom CrystalHD hardware based video decoder to improve the performance of video decode.
debug Instructs Qt to use the 'debug' target instead of 'release' target. If your MythTV is crashing or you need a backtrace, you need to compile it with this option otherwise the debugging data is useless.
dvb Enables support for Linux DVB cards. These include all cards that work with digital signals such as ATSC, DVB-T, DVB-C, and DVB-S, QAM-64, and QAM-256.
egl Support EGL video output.
fftw Support visualizations via sci-libs/fftw
hls HTTP Live Streaming support
ieee1394 Allows MythTV to communicate and use Firewire enabled Cable boxes. These are typically found in the United States, where such support is required by law. This will also install Firewire test programs and external channel changers if the internal changer does not work.
jack Allows MythTV to use JACK as your sound output device. You will have to manually configure the path to your JACK settings.
lcd Tells MythTV that you have an instance of app-misc/lcdproc configured on your machine and it should output information such as current time, show name, episode name, etc to that LCD.
lirc Adds LIRC support directly to MythTV allowing for built in control via a LIRC device.
perl Builds the perl bindings for MythTV. Allows you to write scripts in Perl to control your MythTV setup or communicate with it.
raop Remote Audio Output Protocol (aka AirTunes/AirPlay)
wrapper Use Ubuntu mythtfrontend wrapper.
xmltv Pulls in the media-tv/xmltv TV listing grabbers for users not using Schedules Direct.

tvbrowser

themes Install extra theme packs

tvheadend

ccache Use dev-util/ccache
dvbscan Use media-tv/linuxtv-dvb-apps
imagecache Enable support for image caching
uriparser Use dev-libs/uriparser
xmltv Use media-tv/xmltv

v4l-dvb-saa716x

firmware Install firmware

xawtv

xext Enable use of XFree extensions (DGA,VidMode,DPMS)
zvbi Enable VBI Decoding Library for Zapping

xbmc

airplay enable AirPlay support
bluray Enable playback of Blu-ray filesystems
cec Enable support for HDMI-CEC devices via libcec
fishbmc Enable fishBMC visualization plugin
gles Enable support for GLES
goom Enable GOOM visualization plugin
midi Support MIDI files
nfs Enable NFS client support
projectm Enable projectM visualization plugin
pvr Enable MythTV support
rsxs Enable really slick X screensavers
rtmp Enable Real Time Messaging Protocol using librtmp
sftp Support browsing files over SFTP
webserver Enable internal webserver
xrandr Support X randr extension

xmltv

ar Argentina tv listing grabber
ch Switzerland bluewin tv listing grabber
dk Denmark tv listing grabber
dtvla Latin America digital tv listing grabber
ee Estonia tv listing grabber
es_laguiatv Spain alternative grabber
es_miguiatv Spain alternative grabber
eu_epg EPG grabber for some European countries.
fi Finland tv listing grabber
fr France tv listing grabber
hr Croatia tv listing grabber
huro Hungarian tv listing grabber
il Israel tv listing grabber
in India tv listing grabber
is Iceland tv listing grabber
it Italy tv listing grabber
na_dd North America tv listing grabber
na_dtv North America Direct TV grabber
na_icons option for na_dd to download icons
nl Netherlands tv listing grabber
no_gf Norway Gfeed tv listing grabber
pt Portugal tv listing grabber
re Reunion Island (France) tv listing grabber
se_swedb Sweden tv listing grabber
tv_check enable GUI checking
tv_combiner enable grabbers combiner
tv_pick_cgi enable CGI support
uk_bleb Britain tv listing grabber
uk_rt Britain alternative tv listing grabber
za South Africa tv listing grabber

media-video

aravis

X Build the GTK+-based video viewer for aravis. This requires GStreamer and a few plugins but technically not the GST plugin for aravis.
gstreamer Build the GStreamer plugin for aravis, but not the video viewer.

arista

faac Use external faac library for AAC encoding
nautilus Add an entry in the Nautilus context menu to transcode media files for a specified device.

avidemux

aften Enable A/52 (AC-3) audio encoder support.
amr Enable Adaptive Multi-Rate format support via media-libs/opencore-amr.
vpx Enable VP8 codec support via media-libs/libvpx.

bombono-dvd

gnome Use GVFS for desktop integration

chaplin

transcode Enable DVD ripping and transcoding

clive

clipboard Support reading from X clipboard
pager Support pager!?
password Support password controlled sites

devede

mencoder Prefer MPlayer mencoder over Libav avconv or FFmpeg ffmpeg for encoding.

dv2sub

kino install kino plugin

dvd-slideshow

themes Install theme pack

dvdauthor

graphicsmagick Use media-gfx/graphicsmagick instead of media-gfx/imagemagick

dvdrip

fping Enables fping support for cluster rendering
subtitles Enables support for subtitle ripping

ffdiaporama

openclipart Support openslipart database
texturemate Install extra backgrounds

ffmpeg

aacplus AAC+ encoding via media-libs/libaacplus.
amr Enables Adaptive Multi-Rate Audio support
amrenc Enables Adaptive Multi-Rate Audio encoding support with media-libs/vo-amrwbenc.
armv5te Enables optimizations for armv5te processors.
armv6 Enables optimizations for armv6 processors.
armv6t2 Enables optimizations for armv6t2 processors.
armvfp Enables VFP optimizations for ARM processors.
bluray Enable playback of Blu-ray filesystems
bs2b Enables media-libs/libbs2b based Bauer stereo-to-binaural filter.
cdio Enables audio CD grabbing with dev-libs/libcdio.
celt Adds Xiph CELT audio decoding support via media-libs/celt
cpudetection Enables runtime CPU detection (useful for bindist, compatibility on other CPUs)
faac Use external faac library for AAC encoding
fdk Use external fdk-aac library for AAC encoding
flite Adds a text-to-speech filter based on app-accessibility/flite.
frei0r Enable frei0r wrapping in libavfilter
fribidi Enables fribidi support in the drawtext filter.
gme Enables support for media-libs/game-music-emu for playing various video game music formats.
gpl Build GPL code. Should be enabled unless you require LGPL binaries.
hardcoded-tables Use pre-calculated tables rather than calculating them on the fly.
iec61883 Support for FireWire DV/HDV input device using media-libs/libiec61883.
libsoxr Enables audio resampling through media-libs/soxr.
libv4l Uses media-libs/libv4l for video4linux instead of direct calls. Adds support for more devices via the userspace library.
mips32r2 Enables MIPS32R2 optimizations.
mipsdspr1 Enables MIPS DSP ASE R1 optimizations.
mipsdspr2 Enables MIPS DSP ASE R2 optimizations.
mipsfpu Enables floating point MIPS optimizations.
network Enables network streaming support
openssl Enables dev-libs/openssl support. Adds support for encrypted network protocols (TLS/HTTPS).
opus Adds (decoding) support for the Opus codec via media-libs/opus.
pic Force shared libraries to be built as PIC (this is slower)
postproc Build and install libpostproc.
quvi Adds support for playing media from Internet services using the quvi project.
rtmp Enable Real Time Messaging Protocol using librtmp
schroedinger Enable Dirac video support (an advanced royalty-free video compression format) via libschroedinger (high-speed implementation in C of the Dirac codec).
snappy Enable app-arch/snappy support. Required for e.g. Vidvox Hap encoder.
ssh Enable SSH/sftp support via net-libs/libssh.
twolame Enables MP2 encoding via media-sound/twolame as an alternative to the internal encoder.
vpx Enables vp8 codec support using libvpx: Decoding vp8 does not require this to be enabled but libvpx can also be used for decoding; encoding vp8 requires this useflag to be enabled though.
webp Enables WebP encoding with media-libs/libwebp.
x265 Enables HEVC encoding with media-libs/x265.
zvbi Enables media-libs/zvbi based teletext decoder.

ffmpeg2theora

kate Adds support for Ogg Kate subtitles via libkate.

gnome-mplayer

dconf Enable support for gnome-base/dconf
gda Enable support for gnome-extra/libgda

google2srt

html Install HTML documentation

h264enc

ogm Support for OGM container format

handbrake

fdk Support for encoding AAC using media-libs/fdk-aac.
ffmpeg Use FFmpeg from media-video/ffmpeg to decode MPEG-2 instead of media-plugins/gst-plugins-mpeg2dec.
gstreamer Support for the streaming media framework from media-libs/gstreamer.
gtk Support for Gimp ToolKit + from x11-libs/gtk+, requirement for a GUI-based HandBrake.
libav-aac Support for encoding AAC using media-libs/libav's internal encoder.

kdenlive

nepomuk Enable Nepomuk based semantic desktop support (deprecated)

kino

gpac Enable GPAC support when exporting to 3GPP format

kmplayer

npp Compile the npp backend that plays xembed style browser plugins.

libav

aac Use external vo-aacenc library for AAC encoding
amr Enable Adaptive Multi-Rate Audio support
armv5te Enable optimizations for armv5te processors
armv6 Enable optimizations for armv6 processors
armv6t2 Enable optimizations for armv6t2 processors
armvfp Enable VFP optimizations for ARM processors
bs2b Enable media-libs/libbs2b based Bauer stereo-to-binaural audio filter
cdio Enable audio CD grabbing with dev-libs/libcdio.
cpudetection Enables runtime CPU detection (useful for bindist, compatibility on other CPUs).
faac Use external faac library for AAC encoding
fdk Use external fdk-aac library for AAC encoding and decoding
frei0r Enable frei0r wrapping in libavfilter
gpl Build all GPL licensed code. Without this flag set the package is build under LGPL license.
hardcoded-tables Use pre-calculated tables rather than calculating them on the fly.
network Enable network streaming support.
openssl Prefer dev-libs/openssl over net-libs/gnutls to provide SSL/TLS support (notice: the resulting binaries are unredistributable).
opus Use the external opus library for encoding and decoding.
pic Force shared libraries to be built as PIC (this is slower).
pulseaudio Enable pulseaudio input support.
rtmp Enable Real Time Messaging Protocol using librtmp instead the native implementation.
schroedinger Enable Dirac video support (an advanced royalty-free video compression format) via libschroedinger (high-speed implementation in C of the Dirac codec).
ssl Enable SSL/TLS support using dev-libs/openssl or dev-libs/gnutls.
tools Build and install small tools like aviocat, cws2fws, graph2dot, ismindex, qt-faststart.
twolame Enable MP2 encoding via media-sound/twolame as an alternative to the internal encoder
vis Adds support for SIMD optimizations for UltraSPARC processors.
vpx Enable vp8 encoding support using libvpx.
webp Enable WebP encoding with media-libs/libwebp.
x265 Enable HEVC encoding with media-libs/x265.

lives

libvisual Enable libvisual support

minitube

download Enable support for downloading YouTube videos

mjpegtools

sdlgfx Enables y4mhist to display a graphical histogram

mjpg-streamer

input_control Plugin giving ability to control camera movement (only specific cameras)
input_file Plugin that watches given directory and send it's content
input_testpicture Plugin for sending compiled in, test pictures
input_uvc Plugin that sends video stream from UVC compatible camera
output_autofocus Auto focusing plugin
output_file Plugin that saves received content under given location
output_http Small HTTP server plugin which sends WWW directory content and streams image content
output_rtsp Plugin which provides a mechanism to take snapshots with a trigger from a UDP packet
output_udp Plugin receiving content over UDP and storing to a directory
v4l Uses media-libs/libv4l function mapping for input_uvc plugin
www Installs WWW content

motiontrack

multiprocess Enables multi-process support (SMP/cluster) for motiontrack programs

mplayer

bl Blinkenlights video output
bluray Enable playback of Blu-ray filesystems
bs2b Enable Bauer stereophonic-to-binaural headphone filter
cdio Use libcdio for CD support (instead of cdparanoia)
cpudetection Enables runtime CPU detection (useful for binpkgs, compatibility on other CPUs)
dvdnav Use forked libdvdnav, navigate menus in GUIs
enca Enables support for charset discovery and conversion
faac Use external faac library for AAC encoding
faad Use external faad library for AAC decoding
libmpeg2 Build support for mpeg2 over media-libs/libmpeg2 rather than using ffmpeg.
live Enables live.com streaming media support
md5sum Enables md5sum video output
mng MNG input support
network Enables network streaming support
nut Enables support for the NUT container format
osdmenu Enables support for on-screen display (OSD) menus
pnm Add PNM video output option, to create PPM/PGM/PGMYUV images
pvr Enable Video4Linux2 MPEG PVR
radio Enable V4L2 radio interface and support
rar Enable Unique RAR File Library
rtc Enables usage of the linux real time clock. The alternative is software emulation of rtc
rtmp Enables RTMPDump Streaming Media support
shm Enable support for shm
tga Enables Targa video output
toolame Enable toolame MPEG-2 encoding
tremor Enable internal support for Vorbis
twolame Enable twolame MPEG-2 encoding
vidix Support for vidix video output
xanim Enables support for xanim based codecs
xvmc Enables X-Video Motion Compensation support
zoran Enables ZR360[56]7/ZR36060 video output

mpv

bluray Enable playback of Blu-ray filesystems
bs2b Enable Bauer stereophonic-to-binaural headphone filter
cdio Enable CDDA support via dev-libs/libcdio-paranoia
cli Build mpv CLI player
doc-pdf Build documentation in pdf format
drm Enable Kernel Mode Setting / Direct Rendering Manager based video output
dvdnav Enable support for DVD navigation using media-libs/libdvdnav
egl Enable EGL backend for X11 OpenGL video output (experimental)
enca Enable support for charset discovery and conversion using app-i18n/enca
jpeg Enable support for saving screenshots to JPEG format
libguess Enable support for charset discovery and conversion using app-i18n/libguess
libmpv Build mpv shared library
lua Enable Lua scripting, OSC (On Screen Controller) GUI and net-misc/youtube-dl hook-script
luajit Use dev-lang/luajit instead of dev-lang/lua
mpg123 Enable support for mp3 decoding via media-sound/mpg123 instead of relying on ffmpeg support
postproc Enable image post-processing via libpostproc
pvr Enable Video4Linux2 MPEG PVR
quvi Enable support for streaming sites using media-libs/libquvi
radio Enable V4L2 radio interface and support
raspberry-pi Enable support for the Raspberry Pi
rubberband Enable high quality pitch correction via media-libs/rubberband
sdl Enable media-libs/libsdl2 based video and audio outputs
shm Enable support for shm
vf-dlopen Install additional video filters for using with -vf dlopen

noad

libmpeg2 Support for libmpeg2 library

ogmrip

ogm Support for OGM container format
srt Support for SRT subtitle format

parole

clutter Compile in Clutter GTK+ support

pgcedit

video Add support for video preview

plasma-mediacenter

nepomuk Enable Nepomuk based semantic desktop support (deprecated)

qgifer

imagemagick Use imagemagick for image operations

rtmpdump

gnutls Use GnuTLS library instead of the default OpenSSL
polarssl Use PolarSSL library instead of the default OpenSSL

smplayer

autoshutdown Enable the option to shutdown your computer after finishing the playlist. This requires dev-qt/qtdbus as dependency.
mpris Enable support for MPRIS2 (Media Player Remote Interfacing Specification, version 2), a DBus interface for remote control, which requires dev-qt/qtdbus as dependency.
streaming Support for streaming video sites through net-misc/youtube-dl (MPV only).

totem

lirc Enable support for controlling Totem with a remote control using app-misc/lirc
nautilus Enable the nautilus extension
python Build support for dev-lang/python plugins
zeitgeist Build the plugin to inject events to gnome-extra/zeitgeist

transcode

mjpeg Enables mjpegtools support
nuv NuppelVideo container format demuxing
pic disable optimized assembly code that is not PIC friendly
postproc Build with ffmpeg libpostproc support

tsmuxer

qt4 Installs tsMuxerGUI (needs Qt4)

ushare

dlna Add DLNA (media-libs/libdlna) support

vdr

alternatechannel Use alternate channel on record
bidi fribid support, for languages, written from right to left
ddepgentry remove duplicate EPG entries
dvlvidprefer controls video-dir choice on recording
graphtft support for media-plugins/vdr-grapftftplugin up from vdr-graphtft-0.1.7
html Install HTML documentation
jumpingseconds skip seconds in played records
jumpplay Enables automatic jumping over cut marks while watching a recording
kbd enable keyboard support as remote device
mainmenuhooks Allows to replace main menu entries by some special plugins (like epgsearch, extrecmenu, ...)
menuorg Enables support for the media-plugins/vdr-menuorg
menuselection adds support for menu hotkeys of double digits
naludump Removes NALU fill data from h.264-Streams of TS files
permashift permanent timeshift by recording live TV on hard disk, need plugin media-plugins/vdr-vdr-permashift
permashift_v1 permanent timeshift by recording live TV on RAM, need plugin >=mediaplugins/vdr-permashift-1
pinplugin Support for media-plugins/vdr-pin
resumereset rreset resume of EOF