How To Compile A Kernel - The Ubuntu Way
Version 1.0
Author: Falko Timme <ft [at] falkotimme [dot] com>
Last edited 11/05/2006
Each distribution has some specific tools to build a custom kernel
from the sources. This article is about compiling a kernel on Ubuntu
systems. It describes how to build a custom kernel using the latest
unmodified kernel sources from www.kernel.org (vanilla kernel) so that you are independent from the
kernels supplied by your distribution. It also shows how to patch the
kernel sources if you need features that are not in there.
I have tested this on Ubuntu 6.10 Server ("Edgy Eft") and Ubuntu 6.06
Desktop ("Dapper Drake").
I want to say first that this is not the only way of setting up such a
system. There are many ways of achieving this goal but this is the way I
take. I do not issue any guarantee that this will work for you!
1 Preliminary Note
I prefer to do all the steps here as the root
user. So if you haven't already created a root login, you should do so
now:
sudo passwd root
Afterwards, log in as root:
su
If you would like to work as a normal user instead of root, remember
to put sudo in front of all the commands
shown in this tutorial. So when I run
apt-get update
you should run
sudo apt-get update
instead, etc.
1.1 /bin/sh on Ubuntu 6.10 ("Edgy Eft")
On Ubuntu 6.10, /bin/sh is a symlink to /bin/dash by default. /bin/dash
seems to make problems when you compile software from the sources, at
least I had that impression. That's why I make /bin/sh
a symlink to /bin/bash instead.
If you are on Ubuntu 6.10, you should do this now:
rm -f /bin/sh
ln -s /bin/bash /bin/sh
2 Install Required Packages For Kernel Compilation
First we update our package database:
apt-get update
Then we install all needed packages like this:
apt-get install kernel-package libncurses5-dev
fakeroot wget bzip2
3 Download The Kernel Sources
Next we download our desired kernel to /usr/src.
Go to www.kernel.org and
select the kernel you want to install, e.g. linux-2.6.18.1.tar.bz2
(you can find all 2.6 kernels here: http://www.kernel.org/pub/linux/kernel/v2.6/).
Then you can download it to /usr/src like
this:
cd /usr/src
wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.18.1.tar.bz2
Then we unpack the kernel sources and create a symlink linux to the
kernel sources directory:
tar xjf linux-2.6.18.1.tar.bz2
ln -s linux-2.6.18.1 linux
cd /usr/src/linux
4 Apply Patches To The Kernel Sources (Optional)
Sometimes you need drivers for hardware that isn't supported by the
new kernel by default, or you need support for virtualization techniques
or some other bleeding-edge technology that hasn't made it to the
kernel yet. In all these cases you have to patch the kernel sources
(provided there is a patch available...).
Now let's assume you have downloaded the needed patch (I call it patch.bz2 in this example) to /usr/src. This is how you apply it to your kernel
sources (you must still be in the /usr/src/linux
directory):
|  |
bzip2 -dc /usr/src/patch.bz2 | patch -p1 --dry-run
bzip2 -dc /usr/src/patch.bz2 | patch -p1
The first command is just a test, it does nothing to your sources. If
it doesn't show errors, you can run the second command which actually
applies the patch. Don't do it if the first command shows errors!
You can also apply kernel prepatches to your kernel sources. For
example, if you need a feature that is available only in kernel
2.6.19-rc4, but the full sources haven't been released yet for this
kernel. Instead, a patch-2.6.19-rc4.bz2 is
available. You can apply that patch to the 2.6.18 kernel sources, but
not to kernel 2.6.18.1 or 2.6.18.2, etc. This is explained on http://kernel.org/patchtypes/pre.html:
Prepatches are the equivalent to alpha releases for Linux; they
live in the testing directories in the archives. They should be applied
using the patch(1) utility to the source code of the previous full
release with a 3-part version number (for example, the 2.6.12-rc4
prepatch should be applied to the 2.6.11 kernel sources, not, for
example, 2.6.11.10.)
So if you want to compile a 2.6.19-rc4 kernel, you must download the
2.6.18 kernel sources (http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.18.tar.bz2)
in step 3 instead of kernel 2.6.18.1!
This is how you apply the 2.6.19-rc4 patch to kernel 2.6.18:
cd /usr/src
wget
http://www.kernel.org/pub/linux/kernel/v2.6/testing/patch-2.6.19-rc4.bz2
cd /usr/src/linux
bzip2 -dc /usr/src/patch-2.6.19-rc4.bz2 | patch -p1 --dry-run
bzip2 -dc /usr/src/patch-2.6.19-rc4.bz2 | patch -p1
