2004.03_Installing the 2.6 Kernel-a Step-by-Step Guide.pdf

SYSADMIN

Kernel 2.6 Installation

Chief Installer

Improved support for multimedia

applications, enhanced system per-

formance, better hardware support,

and the new IPsec security module to

improve system security. There are

many good reasons to start using the

latest kernel now. We show you how

with a step by step guide.

BY EVA-KATHARINA KUNST

AND JÜRGEN QUADE

32 MByte archive: the new kernel’s

figures are certainly impressive [1],

although configuring and installing the

kernel is certainly non-trivial. That said,

if you have some experience of compil-

ing and configuring the 2.4 kernel, you

should have no difficulty finding your

way around in 2.6. A word of warning to

kernel newbies, however. A kernel

update is a far-reaching system modifica-

tion that will punish any unconsidered

steps.

The following article points out

a direct path to a functional kernel

2.6. Tuning the kernel to reflect your sys-

tem environment requires a bit more

patience. For additional information,

refer to the Post-Halloween Document by

Dave Jones at [2] (a useful resource) and

also the kernel mailing list archive at [4].

In contrast to many projects on this

scale, no special tools are required to

build your own kernel. Useable versions

of the required ingredients – a compiler,

an assembler, and make – are available

on nearly any Linux system. If in doubt,

Kernel 2.6 under Suse

SuSE 9.0 is kernel 2.6 ready. A 2.6 test kernel

is supplied with the distribution, and newer

versions will be available at [7]. However, the

/usr/sbin/hwbootscan may cause some

issues in combination with a 2.6 kernel. You

should disable the program in this case. To

do so, disable the HWBOOTSCAN_BIN vari-

able in line 20 of the /etc/init.d/hwscan

script as follows.

# HWBOOTSCAN_BIN= U

/usr/sbin/hwbootscan

The kernel 2.6 supplied with the distribution

makes it easier for you to build your own ker-

nel, as the existing configuration can be

used as a template. Use rpm to install the

test kernel (YaST cannot do this). Then copy

the 2.6 kernel configuration file to the direc-

tory with the current Linux sources:

cp vmlinuz-2.6.0-test5-5- U

default.config /usr/src U

/linux-2.6.1-test11/

After copying the file, re-run make menucon-

fig . This simply adds any new options

automatically to the kernel configuration.

For this, and the following steps, ensure that

the developer tools, GCC, make, ncurses and

Qt3-devel for make xconfig are installed

After configuring the kernel, follow steps 5

through 8 as defined in the text. You may

need to edit /etc/modprobe.conf after load-

ing some modules.

Suse stores additional entries in the

/etc/modprobe.conf.local file. The syntax

for this configuration file is described in

the manpages ( man modprobe.conf ).

Eva-Katharina Kunst is a journalist,

and Jürgen Quade a professor at the

Hochschule Niederrhein. Both have

been keen Open Source supports

since the early days of Linux.

March 2004

www.linux-magazine.com

Installing the kernel 2.6 – a step-by-step guide

F ive million lines of code packed in a

Kernel 2.6 Installation

SYSADMIN

Step 1

Check modutils,

configure modprobe

Non Debian systems can

download a current ver-

sion of the modutils from

[3], for example 3.0-pre5.

Expanding the program

package will create a

module-init-tools-3.0-pre5

directory that contains a

README file with a

slightly terse description

of the most important

details. For one thing, the

file tells you that you will

need to run the following

commands:

New Configuration Files

The new modutils require a new configu-

ration file: /etc/modprobe.conf . If this file

is not available on your machine, you

should use ./generate-modprobe.conf

/etc/modprobe.conf to create it. If you are

a fan of the device filesystem, you will

also want to copy modprobe.devfs to the

/etc/ directory.

After fulfilling these requirements, you

can continue with step 2 (see Figure 1).

This means retrieving the 2.6 kernel

sources off the Web. The welcome page

of the kernel archive [1] lists the current

versions. To access the full sources rather

than a patch, ensure that you click on the

F (for Full), which is hiding on the right

of 2.6.1-test11 (see Figure 2). Store the

sources in the /usr/src directory (Step 3):

Step 2

Load kernel sources

(www.kernel.org)

Step 3

Unpack sources

"tar xvfj linux-2.6.0.bz2"

Step 4

Configure

"make menuconfig"

Step 5

Generate

"make all"

Step 6

Install kernel

(with Lilo or Grub)

Step 7

Install modules

"make modules_install"

./configure -- U

prefix=/

make moveold U

# Only for the first U

round!

make

make install

Step 8

Boot and test

cd /usr/src

tar xvfj /tmp/ U

linux-2.6.1-

test11.tar.bz2

Figure 1: Eight steps to your own kernel. Kernel newbies may need

to get used to performing steps 4 through 8 more than once.

you can install the developer packages. It

does not really matter whether you use

GCC version 2.95, 3.2, or 3.3, and make

version 3.80 to compile and build the

kernel. Kernel 2.6 is fairly insensitive to

version numbers. When we compiled the

kernel on our Debian system, we were

equally successful with all three com-

piler versions.

In contrast, modutil dependencies

need to be taken seriously (step 1 in Fig-

ure 1). The modutils are responsible for

loading and unloading the kernel mod-

ules, but the Linux developers have

completely re-designed this mechanism.

Kernel 2.6 modules need the latest ver-

sion of the insmod to load.

The new insmod will call the older

variant if necessary. This explains why

the older insmod.old version needs to be

kept. You can easily find out whether a

2.6 aware version of this program is

installed. If you find a program called ins-

mod.old below /sbin/ or /usr/local/sbin ,

insmod should be able to handle the new

kernel. Fortunately, many current distrib-

utions take care of this (for example Suse

8.2 and 9.0). If this is not the case,

Debian (or Knoppix) users can launch

apt-get to install the new modutils.

The original program,

/sbin/insmod , is moved to /sbin/insmod.

old . The new /sbin/insmod calls the pre-

vious version, if your system boots a

kernel 2.4, but follows the new specifica-

tion when loading kernel 2.6 modules.

The same applies to the /sbin/rmmod

and /sbin/modprobe programs.

The most difficult and time-consuming

step (number 4) follows immediately

after unpacking the archive: the kernel

configuration. In our opinion, make

menuconfig is best suited to this task

(see Figure 3). The command creates

and launches an ncurses-based configu-

apt-get install U

module-init-tools

Figure 2: The kernel archive has a complete collection of kernel versions. The welcome page has a link to

the current kernel. Previous versions are accessible via the links in the table at the top.

www.linux-magazine.com

March 2004

SYSADMIN

Kernel 2.6 Installation

through the menu, the process can take a

good two or three hours. But that is

nothing in comparison to the more than

5 million lines of code that this process

configures.

If you have a previous working 2.6

kernel configuration (see the “Kernel 2.6

under Suse” box), you should base your

new configuration on it. Otherwise, go

for a minimalist approach: Select only

those components that you require

urgently. Once you have the kernel run-

ning, you can add new features and

drivers at any time later.

Figure 3: Configuring the kernel has become a lot more understandable despite the number of options

available for 2.6. The picture shows the menuconfig configuration tool at work.

Generation

After storing your settings in the configu-

ration file, you can go on to generate the

kernel. Debian or Knoppix users should

refer to the “Steps 5 through 7 on

Debian” box.

All other users should enter make all

in the source directory (step 5). You can

ignore any warnings displayed on

screen. On a system with a lot of mem-

ory, and a 2.6GHz Intel processor, you

can expect to see the prompt again in

about 10 minutes.

If the kernel generation process quits

unexpectedly, you will need to inspect

the output to discover the cause and

then re-configure the kernel (by calling

make menuconfig ). Ensure that you dis-

able the troublesome component.

ration program that you can run in any

normal console window. A graphical

variant based on Qt is also available (see

Figure 4): To use this version, enter

make xconfig .

default configuration for the processor

type ( Processor type and features menu)

and the accompanying system architec-

ture. Watch out for filesystems: If you are

a Suse user, you will definitely need Reis-

erFS support . If you do not need specific

components (such as the SCSI subsys-

tem), you should disable them.

Help is available for almost every

point. The first time you work your way

Patience

Despite a mass of new options, the con-

figuration process has become more

intuitive. Make sure that you change the

Steps 5 through 7

on Debian

The unstable version of Debian (Sarge)

offers a number of kernel 2.6 downloads.

But tuning and building a kernel that will

provide optimal support for your system

does require a few manual steps. After com-

pleting the configuration (step 4) call

make-kpkg in the source code directory:

./make-kpkg kernel_image

This script generates the kernel and mod-

ules (step 5) and creates the Debian

kernel_image package in a directory below

the source directory (typically /usr/src/ ).

Before you install this (steps 6 and 7), you

should add a new option to your boot

loader. When you run dpkg -i kernel-image-

Kernelversion.deb to install the image

package, the Debian installer also launches

lilo . This should introduce lilo to the new ker-

nel, and allow the boot loader to display this

boot option.

Figure 4: The Qt-based xconfig provides a useful overview. The configuration areas are shown on the

left, the individual options at the top, and below them the help texts for the current parameter.

March 2004

www.linux-magazine.com

Kernel 2.6 Installation

SYSADMIN

Installation

If everything worked out fine, the in-

stallation – steps 6 and 7 – are next.

Installing the modules is easy. Just call

make modules_install , and the modules

will appear in a new directory called

/lib/modules/2.6.1-test11/ a few minutes

later. But you will need to copy the

kernel manually to your /boot/ directory:

boot loader, don’t forget to run lilo when

ever you install a new kernel.

graphics adapters are just one example.

For more information see [8].

Check the boot messages next. Run-

ning dmesg allows you to review older

messages. If some issues are found, go

back to step 4. If not, you have a work-

ing kernel 2.6. Well done!

Test Boot

So let’s boot the machine. If the kernel

fails to complete the boot process, you

will have to evaluate the output on the

console. These messages almost always

provide the reason why the kernel has

failed to boot. In many cases, a required

driver will be missing, and that could

prevent access to the hard disk, or the

root filesystem, for example.

If the screen simply stays blank, trou-

bleshooting may be tricky. This is

typically an issue with the framebuffer

device. There are two things you can do:

•Remove the vga=XXX option from

/etc/lilo.conf , or enable vga=normal .

• Check whether the CONFIG_VT option

is set to y in the kernel configuration

file, /usr/src/linux-2.6.1-test11/.config .

If you succeed in booting the new kernel,

you may need to create a few device dri-

vers for any of your components that the

default kernel does not support. nVidia

■

INFO

cp /usr/src/linux-2.6.1-test11 U

/arch/i386/boot/bzImage /boot U

/vmlinuz-2.6.1

[1] Kernel sources: http://www.kernel.org

[2] Dave Jones,“The Post-Halloween

Document”: http://www.linux.org.uk/

~davej/docs/post-halloween-2.6.txt

[3] New modutils: http://www.kernel.org/

pub/linux/kernel/people/rusty/modules/

[ 4] Linux Kernel mailing list: http://lkml.org

[5] Lilo: http://lilo.go.dyndns.org/

[6] Grub: http://www.gnu.org/software/

grub/grub.html

[7] Kernel 2.6 packages for Suse 9.0:

ftp://ftp.suse.com/pub/suse/i386/9.0/

unsorted/kernel-2.6/

[8] nVidia kernel modules:

http://www.minion.de/

The boot loader should have an option

for the new kernel when you fire up your

machine. For lilo [5] this means editing

/etc/lilo.conf , and for grub [6] the

/boot/grub/menu.lst file. Add a new

entry with the name of the kernel (for

example /boot/vmlinuz-2.6.1 ) and a

symbolic name for the menu item. You

only need to do this once.

If you later add a new driver to the

kernel, it is typically unnecessary to edit

lilo.conf and menu.lst . If you use the lilo

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