Gentoo Logo

Disclaimer : This handbook has been replaced by a newer version and is not maintained anymore.


[ << ] [ < ] [ Home ] [ > ] [ >> ]


7. Configuring the Kernel

Content:

7.a. Timezone

You first need to select your timezone so that your system knows where it is located. Look for your timezone in /usr/share/zoneinfo, then copy it to /etc/localtime. Please avoid the /usr/share/zoneinfo/Etc/GMT* timezones as their names do not indicate the expected zones. For instance, GMT-8 is in fact GMT+8.

Code Listing 1.1: Setting the timezone information

# ls /usr/share/zoneinfo
(Suppose you want to use GMT)
# cp /usr/share/zoneinfo/GMT /etc/localtime

7.b. Installing the Sources

Choosing a Kernel

The core around which all distributions are built is the Linux kernel. It is the layer between the user programs and your system hardware. Gentoo provides its users several possible kernel sources. A full listing with description is available at the Gentoo Kernel Guide.

For sparc-based systems we have sparc-sources (2.4 kernel sources optimized for SPARC users) and gentoo-sources (recommended 2.6 kernel sources).

In the next example we install the gentoo-sources. Of course substitute with your choice of sources, this is merely an example.

Code Listing 2.1: Installing a kernel source

# emerge gentoo-sources

When you take a look in /usr/src you should see a symlink called linux pointing to your kernel source. In this case, the installed kernel source points to linux-2.6.17-gentoo-r5. Your version may be different, so keep this in mind.

Code Listing 2.2: Viewing the kernel source symlink

# ls -l /usr/src/linux
lrwxrwxrwx    1 root     root       12 Oct 13 11:04 /usr/src/linux -> linux-2.6.17-gentoo-r5

Now it is time to configure and compile your kernel source.

7.c. Manual Configuration

Introduction

Manually configuring a kernel is often seen as the most difficult procedure a Linux user ever has to perform. Nothing is less true -- after configuring a couple of kernels you don't even remember that it was difficult ;)

However, one thing is true: you must know your system when you start configuring a kernel manually. Most information can be gathered by emerging pciutils (emerge pciutils) which contains lspci. You will now be able to use lspci within the chrooted environment. You may safely ignore any pcilib warnings (like pcilib: cannot open /sys/bus/pci/devices) that lspci throws out. Alternatively, you can run lspci from a non-chrooted environment. The results are the same. You can also run lsmod to see what kernel modules the Installation CD uses (it might provide you with a nice hint on what to enable).

Now go to your kernel source directory and execute make menuconfig. This will fire up an ncurses-based configuration menu.

Code Listing 3.1: Invoking menuconfig

# cd /usr/src/linux
# make menuconfig

You will be greeted with several configuration sections. We'll first list some options you must activate (otherwise Gentoo will not function, or not function properly without additional tweaks).

Activating Required Options

First of all, activate the use of development and experimental code/drivers. You need this, otherwise some very important code/drivers won't show up:

Code Listing 3.2: Selecting experimental code/drivers

Code maturity level options --->
  [*] Prompt for development and/or incomplete code/drivers

Now go to File Systems and select support for the filesystems you use. Don't compile them as modules, otherwise your Gentoo system will not be able to mount your partitions. Also select Virtual memory and /proc file system. If you are running a 2.4 kernel, you should also select /dev file system + Automatically mount at boot:

Code Listing 3.3: Selecting necessary file systems

File systems --->
  [*] Virtual memory file system support (former shm fs)
  [*] /proc file system support
  [ ] /dev/pts file system for Unix98 PTYs

(Select one or more of the following options as needed by your system)
  <*> Ext3 journalling file system support
  <*> Second extended fs support

If you are using PPPoE to connect to the Internet or you are using a dial-up modem, you will need the following options in the kernel:

Code Listing 3.4: Selecting PPPoE necessary drivers

Network device support --->
  <*> PPP (point-to-point protocol) support
  <*>   PPP support for async serial ports
  <*>   PPP support for sync tty ports

The two compression options won't harm but are not definitely needed, neither does the PPP over Ethernet option, that might only be used by rp-pppoe when configured to do kernel mode PPPoE.

Now activate the correct bus-support:

Code Listing 3.5: Activating SBUS/UPA

Console drivers --->
  Frame-buffer support --->
    [*] SBUS and UPA framebuffers             
      [*] Creator/Creator3D support     (Only for UPA slot adapter used in many Ultras)
    [*] CGsix (GX,TurboGX) support      (Only for SBUS slot adapter used in many SPARCStations)

Of course you want support for the OBP:

Code Listing 3.6: Activating OBP Support

Misc Linux/SPARC drivers --->
  [*]  /dev/openprom device support

You will also need SCSI-specific support:

Code Listing 3.7: Activating SCSI-specific support

SCSI support --->
  SCSI low-level drivers --->
    <*> Sparc ESP Scsi Driver             (Only for SPARC ESP on-board SCSI adapter)
    <*> PTI Qlogic, ISP Driver            (Only for SBUS SCSI controllers from PTI or QLogic)
    <*> SYM53C8XX Version 2 SCSI support  (Only for Ultra 60 on-board SCSI adapter)

To support your network card, select one of the following:

Code Listing 3.8: Activating networking support

Network device support --->
  Ethernet (10 or 100Mbit) --->
    <*> Sun LANCE support                   (Only for SPARCStation, older Ultra systems, and as Sbus option)
    <*> Sun Happy Meal 10/100baseT support  (Only for Ultra; also supports "qfe" quad-ethernet on PCI and Sbus)
    <*> DECchip Tulip (dc21x4x) PCI support (For some Netras, like N1)
  Ethernet (1000Mbit) --->
    <*> Broadcom Tigon3 support (Modern Netra, Sun Fire machines)

When you have a 4-port Ethernet machine (10/100 or 10/100/1000) the port order is different from the one used by Solaris. You can use sys-apps/ethtool to check the port link status.

When you're done configuring your kernel, continue with Compiling and Installing. However, after having compiled the kernel, check its size:

Code Listing 3.9: Check kernel size

# ls -lh vmlinux
-rw-r--r--    1 root     root         2.4M Oct 25 14:38 vmlinux

If the (uncompressed) size is bigger than 2.5 MB (for Sparc32) or 3.5 MB (for Sparc64), reconfigure your kernel until it doesn't exceed these limits. One way of accomplishing this is by having most kernel drivers compiled as modules. Ignoring this can lead to a non-booting kernel.

Also, if your kernel is just a tad too big, you can try stripping it using the strip command:

Code Listing 3.10: Stripping the kernel

# strip -R .comment -R .note vmlinux

Compiling and Installing

Now that your kernel is configured, it is time to compile and install it. Exit the configuration and start the compilation process:

Code Listing 3.11: Compiling the kernel

(sparc32)
# make dep && make clean vmlinux modules modules_install

(sparc64)
# make dep && make clean vmlinux image modules modules_install

When the kernel has finished compiling, copy the kernel image to /boot. Remember to replace <kernel-version> with your actual kernel version.

Code Listing 3.12: Installing the kernel

(sparc32)
# cp vmlinux /boot/<kernel-version>

(sparc64)
# cp arch/sparc64/boot/image /boot/<kernel-version>

Now continue with Installing Separate Kernel Modules.

7.d. Installing Separate Kernel Modules

Configuring the Modules

You should list the modules you want automatically loaded in /etc/modules.autoload.d/kernel-2.6. You can add extra options to the modules too if you want.

To view all available modules, run the following find command. Don't forget to substitute "<kernel version>" with the version of the kernel you just compiled:

Code Listing 4.1: Viewing all available modules

# find /lib/modules/<kernel version>/ -type f -iname '*.o' -or -iname '*.ko'

For instance, to automatically load the 3c59x.o module, edit the kernel-2.6 file and enter the module name in it.

Code Listing 4.2: Editing /etc/modules.autoload.d/kernel-2.6

# nano -w /etc/modules.autoload.d/kernel-2.6

Code Listing 4.3: /etc/modules.autoload.d/kernel-2.6

3c59x

Continue the installation with Configuring your System.


[ << ] [ < ] [ Home ] [ > ] [ >> ]


Print

View all

Page updated March 6, 2007

Summary: The Linux kernel is the core of every distribution. This chapter explains how to configure your kernel.

Sven Vermeulen
Author

Grant Goodyear
Author

Roy Marples
Author

Daniel Robbins
Author

Chris Houser
Author

Jerry Alexandratos
Author

Seemant Kulleen
Gentoo x86 Developer

Tavis Ormandy
Gentoo Alpha Developer

Jason Huebel
Gentoo AMD64 Developer

Guy Martin
Gentoo HPPA developer

Pieter Van den Abeele
Gentoo PPC developer

Joe Kallar
Gentoo SPARC developer

John P. Davis
Editor

Pierre-Henri Jondot
Editor

Eric Stockbridge
Editor

Rajiv Manglani
Editor

Jungmin Seo
Editor

Stoyan Zhekov
Editor

Jared Hudson
Editor

Colin Morey
Editor

Jorge Paulo
Editor

Carl Anderson
Editor

Jon Portnoy
Editor

Zack Gilburd
Editor

Jack Morgan
Editor

Benny Chuang
Editor

Erwin
Editor

Joshua Kinard
Editor

Tobias Scherbaum
Editor

Xavier Neys
Editor

Gerald J. Normandin Jr.
Reviewer

Donnie Berkholz
Reviewer

Ken Nowack
Reviewer

Lars Weiler
Contributor

Donate to support our development efforts.

Copyright 2001-2014 Gentoo Foundation, Inc. Questions, Comments? Contact us.