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5. Installing the Gentoo Installation Files
5.a. Installing a Stage Tarball
Setting the Date/Time Right
Before you continue you need to check your date/time and update it. A
misconfigured clock may lead to strange results in the future!
To verify the current date/time, run date:
Code Listing 1.1: Verifying the date/time
Fri Mar 29 16:21:18 CEST 2005
If the date/time displayed is wrong, update it using the date
MMDDhhmmYYYY syntax (Month, Day, hour, minute
and Year). For instance, to set the date to March 29th, 16:21 in the
Code Listing 1.2: Setting the date/time
# date 032916212010
Making your Choice
The next step you need to perform is to install the stage tarball of
your choice onto your system.
5.b. Downloading the Stage Tarball
Go to the Gentoo mountpoint at which you mounted your filesystems
(most likely /mnt/gentoo):
Code Listing 2.1: Going to the Gentoo mountpoint
# cd /mnt/gentoo
The table below specifies exactly which stages you need for your system.
Stages may be downloaded
off the official Gentoo mirrors under the
All Standard CPU Types
Although we provide stages for little-endian MIPS1, support for little endian
MIPS systems is still restricted to the Cobalt server range. They are provided
for those who may wish to experiment with Gentoo on presently unsupported
platforms, thus it is assumed that you know what you're doing.
If you need to go through a proxy, export the http_proxy and
Code Listing 2.2: Setting proxy information for wget
# export http_proxy="http://proxy.server.com:port"
# export ftp_proxy="http://proxy.server.com:port"
The Gentoo/MIPS netboot images provide wget as a means of downloading
files. Due to space constraints, it is not possible to provide more capable
browsers on SGI netboot images. LiveCD users may use elinks.
Code Listing 2.3: Fetching the tarball via wget
# wget -c http://distfiles.gentoo.org/releases/mips/mips4/stage3-mips4-2008.0.tar.bz2
If you want to check the integrity of the downloaded stage tarball, use
md5sum or sha1sum and compare the output with the MD5 checksum
provided on the mirror. For instance, to check the validity of the mips4 stage
Code Listing 2.4: Example checking integrity of a stage tarball
# md5sum -c stage3-mips4-2008.0.tar.bz2.DIGESTS
# sha1sum -c stage3-mips4-2008.0.tar.bz2.DIGESTS
Unpacking the Stage Tarball
Now unpack your downloaded stage onto your system. We use GNU's tar to
proceed as it is the easiest method:
Code Listing 2.5: Unpacking the stage
# tar -xjpf stage?-*.tar.bz2
Make sure that you use the same options (-xjpf). The x stands for
Extract, the j for Decompress with bzip2, the p for
Preserve permissions and the f to denote that we want to extract
a file, not standard input.
Now that the stage is installed, continue with Configuring the Compile Options.
5.c. Configuring the Compile Options
To optimize Gentoo, you can set a couple of variables which impact Portage
behaviour. All those variables can be set as environment variables (using
export) but that isn't permanent. To keep your settings, Portage provides
you with /etc/make.conf, a configuration file for Portage. It is
this file we will edit now.
A commented listing of all possible variables can be found in
/mnt/gentoo/etc/make.conf.example. For a successful Gentoo
installation you'll only need to set the variables which are mentioned beneath.
Fire up a text editor so we can alter the optimization variables we will discuss
hereafter. Two editors are provided, vi (part of Busybox) and
nano. We will assume you're using nano.
Code Listing 3.1: Opening /etc/make.conf
# nano -w /mnt/gentoo/etc/make.conf
As you probably noticed, the make.conf.example file is
structured in a generic way: commented lines start with "#", other lines define
variables using the VARIABLE="content" syntax. The make.conf
file uses the same syntax. Several of those variables are discussed next.
CFLAGS and CXXFLAGS
The CFLAGS and CXXFLAGS variables define the optimization flags
for the gcc C and C++ compiler respectively. Although we define those
generally here, you will only have maximum performance if you optimize these
flags for each program separately. The reason for this is because every program
In make.conf you should define the optimization flags you think
will make your system the most responsive generally. Don't place
experimental settings in this variable; too much optimization can make
programs behave bad (crash, or even worse, malfunction).
We will not explain all possible optimization options. If you want to know
them all, read the GNU
Online Manual(s) or the gcc info page (info gcc -- only
works on a working Linux system). The make.conf.example file
itself also contains lots of examples and information; don't forget to read it
A first setting is the -march= flag, which specifies the name of the
target architecture. Possible options are described in the
make.conf.example file (as comments). Examples include ISA levels
(mips1 ... mips4) and CPU models (r4400, r4600 ...
etc). For pure ISA level architectures, one can simply specify -mips3
rather than -march=mips3.
Code Listing 3.2: The GCC -march and -mips# settings
A second one is the -O flag (that is a capital O, not a zero),
which specifies the gcc optimization
class flag. Possible classes are s (for size-optimized),
0 (zero - for no optimizations), 1, 2 or even 3 for more
speed-optimization flags (every class has the same flags as the one before, plus
some extras). -O2 is the recommended default. -O3 is known to
cause problems when used system-wide, so we recommend that you stick to
Code Listing 3.3: The GCC O setting
A very important setting in the MIPS world is the -mabi= flag. MIPS has
3 different ABIs: 32 (pure 32-bit, aka o32), 64 (full
64-bit, aka n64) and n32
(a mix of 32-bit data structures with 64-bit instructions). This
flag selects which of these you wish to use. Note you need libraries for the
ABI you select. In layman's terms, this means, for example, you can't use
-mabi=64 on a 32-bit userland (or even an n32 userland).
Another popular optimization flag is -pipe (use pipes rather than
temporary files for communication between the various stages of compilation).
Using -fomit-frame-pointer (which doesn't keep the frame pointer in a
register for functions that don't need one) might have serious repercussions on
the debugging of applications.
When you define the CFLAGS and CXXFLAGS, you should combine
several optimization flags, like in the following example:
Code Listing 3.4: Defining the CFLAGS and CXXFLAGS variable
CFLAGS="-mabi=32 -mips4 -pipe -O2"
You may also want to view the Compilation Optimization Guide for
more information on how the various compilation options can affect your system.
With MAKEOPTS you define how many parallel compilations should occur when
you install a package. A good choice is the number of CPUs (or CPU cores) in
your system plus one, but this guideline isn't always perfect.
Code Listing 3.5: MAKEOPTS for a regular, 1-CPU system
Ready, Set, Go!
Update your /mnt/gentoo/etc/make.conf to your own preference and
save (nano users would hit Ctrl-X). You are now ready to continue
with Installing the Gentoo Base System.
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The contents of this document, unless otherwise expressly stated, are licensed under the CC-BY-SA-2.5 license. The Gentoo Name and Logo Usage Guidelines apply.