Linux.Desktop.Hacks [Electronic resources] نسخه متنی

Hack 89. Upgrade Your Kernel to 2.6

Hot rod your computer with a new
kernel.

Upgrading your kernel
from one minor version to another quickly
becomes old hat. But when a new major series of kernels comes out,
such as the recently released 2.6 kernel series, many people are left
scratching their heads not knowing exactly how they should move to
this new version.

In this hack, you will migrate from a 2.4 series kernel to a 2.6
series. This hack assumes you know how to compile a kernel and that
you have compiled the 2.4 series before [Hack #88] . Starting in mid-2004, most
distributions released 2.6 series kernels. If you
don't want to compile your own 2.6 kernel but you do
want to take advantage of its new features, check your distributions
package manager to see if there is already a 2.6 kernel for you to
use.

10.3.1. Get the Source

The first step is to grab the latest version of the 2.6 kernel from
http://www.kernel.org/, and save
it to /usr/src. Then you should extract it and
rename the resulting directory to linux. If you
have compiled 2.4 before you should rename that source code to
something unique such as linux2.4.

With the source code installed, you should read the
Changes file in
/usr/src/linux/Documentation. This file gives
you a list of points and some notes about the changes you will find
in the new kernel. More importantly, this file contains a list of
software requirements and their minimum version numbers. The file
also includes a command that shows you how to find out what version
of the software is on your system. You should ensure that you check
every piece of software listed, and upgrade your software if
necessary. Do not feel tempted to skip something just because the
version number is similar; the kernel hackers indicate these version
numbers for a reason.

10.3.2. Configure the Code

Although a barrage of new features is included in each new release of
the kernel source, the configuration process has remained largely the
same; you select options from a menu, and decide if they should be
compiled into the kernel or available as loadable modules. What
has changed within the configuration process are
the configuration programs and how they can work for you. The 2.6
kernel experienced an evolution in this area and saw the birth of two
new additions for configuring your kernel. One of these tools is
based on the GTK widget set (used by GNOME), and you can run this
version with the following:

foo@bar:~$ make gconfig

Another available configuration tool uses the Qt widget set (used by
KDE), and you can run this with the following:

foo@bar:~$ make qconfig

Although these two new graphical configuration tools are part of the
2.6 kernel, you can still use make menuconfig for
a console-based menu tool.

Users who are migrating from the 2.4 series kernel to 2.6 can use
their old .config file. To do this simply copy
the .config file from your original 2.4 source
code directory to your new 2.6 directory and run make
oldconfig. This converts the .config
file to one that can be used with the 2.6 kernel.
You'll be asked a lot of questions concerning the
new features in the 2.6 kernel, but most should be fairly simple to
answer.

10.3.3. New Features in 2.6

Version 2.6 has a number of
new
features and improvements that can be useful in the context of
desktop Linux. A huge number of new options are available, and you
should explore them fully and choose the ones most pertinent to your
needs. Here is a summary of some of the most interesting features.

Kernel preemption

The use of kernel preemption produces a lower delay in general
applications and, more specifically, multimedia applications. This is
particularly useful if you want to use your desktop as a sound
recording or video editing workstation.

ALSA

One of the most substantial additions to the 2.6 series is the
Advanced Linux Sound Architecture (ALSA), and it is now the default
sound system for Linux. Although ALSA is within the source tree, you
will need to run through a few additional steps to get it working.
First, you should ensure that you include all the options necessary
for your sound card. To find out what options are necessary, look at
the excellent ALSA web site at http://www.alsa-project.org/alsa-doc, and
select your card from the combo box. Documentation is available for
many of the cards ALSA supports, and this documentation can help you
get the most out of your card.

New filesystems

A number of additional filesystems have made their way into 2.6, and
they include support for ext2,
ext3, reiserfs,
jfs, xfs,
minix, romfs,
iso9660, udf,
msdos, vfat,
ntfs (read-only), adfs,
amiga ffs, Apple Macintosh
hfs, BeOS befs (read-only),
bfs, efs (read-only),
cramfs, free vxfs, OS/2
hpfs, qnx4fs,
sysvfs, and ufs. Although
the kernel is a stable version, you should check that any new
filesystems in 2.6 are fully tested before you store important data
on them.

10.3.4. Compiling the Kernel

When you have configured the
kernel,
you can compile it with this:

foo@bar:~$ make
foo@bar:~$ make modules_install

You no longer need to run make dep, make
modules, and make clean.

10.3.5. Install the Kernel

The compiled kernel is
placed
in
/usr/src/linux/arch/<platform>/boot
and is called bzImage, where
<platform>
is a placeholder for the type of computer on which you are performing
the compile. For example, if you compiled your kernel on an x86
machine, such as a Pentium, Athlon, Celeron, etc., you will find the
kernel image in /usr/src/linux/arch/i386/boot.
You must copy this image over to /boot. You also
should rename it to include the version of the kernel in the filename
so that when you have multiple kernels you can easily tell which is
which. Also, the Linux kernel image has traditionally been referred
to as vmlinuz, and many users continue to call
it this. So, if you have a 2.6.5 kernel, you could copy the file with
this command as root:

foo@bar:~# cp /usr/src/linux/arch/i386/boot/bzImage /boot/vmlinuz-2.6.5

You should also copy the System.map file (this
file has a map of the positions of symbols in the kernel and is used
by programs such as depmod) to the
/boot directory using a similar naming scheme:

foo@bar:~# cp /usr/src/linux/arch/i386/boot/System.map /boot/System.map-2.6.5

To complete the process, just adjust your bootloader to load the new
kernel [Hack #1].