How To Compile A Kernel - The Ubuntu Way

Version 1.0
Author: Falko Timme
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

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Comments

From: at: 2006-11-06 12:25:13

It is absolutely unneccessary to allow root logins by setting a root password in the first step. You can get a root shell without adding insecurity to your system by typing  "sudo bash" or "sudo -i".

From: at: 2006-11-08 15:36:47

As another option - if you want to work fully as root without any lingering settings from your user account, use the following:

sudo su - 

This will give you a "pure" root login with no root password or other changes required from the default Ubuntu setup. 

From: meavaiua at: 2009-08-26 13:45:54

Exactly. You should NEVER EVER create a root login. There is a good reason why this is disabled by default. So just don't. Use sudo su instead.

From: Vladimir at: 2009-09-06 01:12:25

Why

sudo su -

Isn't

sudo -i

enough?

From: at: 2007-01-14 17:15:45

Thank you for this How To.  It helped a lot when I was patching the kernel with the Web100 patch to set up an NDT (Network Diagnostic Tool) server.

From: at: 2007-10-20 03:39:23

Yeah same thing here, great article. I've been wanting to set up an NDT too for a while, so i used it for help with patching.

Dream your life or live your dreams?

 | ramen noodle |

From: at: 2008-02-10 02:58:58

As a newb, when I did the following:

apt-get install kernel-package libncurses5-dev fakeroot wget bzip2

neither package could be located.  After much searching, I figured out because I installed Ubuntu while offline, the Ubuntu setup commented out all the entries in source.list which meant apt-get would always fail.  If any other beginners hit this you can find source.list in /etc/apt/.   If you don't successfully complete this step, you'll no it when make menuconfig fails gloriously.

Thanks, qhawk 

From: at: 2007-06-03 04:00:43

Both Ubuntu and Gentoo obviously have their strength and weaknesses, both will have a place in the Linux world for the foreseeable future and both groups of users need to recognise that. If people were willing to experiment a bit more and use the right tool for the right job, I think there would be a lot less 'fanboyism' and many people would find themselves being a lot more productive. I use Gentoo and Ubuntu, and think it's one of the great advantages of Linux world that I'm not forced to conform with my OS, but can use variants or even make my own if I see the need. Grow up, guys. Oh, and it's better to use 'sudo -s' than set up su, since the latter isn't officially supported or tested and they have the exact same effect.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - | don't buy World of Warcraft Gold, make'em. | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

From: Anonymous at: 2009-11-18 02:44:40
From: Anonymous at: 2010-09-17 01:22:09

From the link above...

"Not that I recommend dispensing with a user account, but I have no user account even on my Ubuntu system."

This guy is an arrogant ignorant (which is the worst combination, ever).

Even distributions with root active (I used to use mandrake 12 years ago) discourage users from running everything as root because it is dangerous. Mandrake had a big warning and a red background whenever running X as root. If you run firefox as root on a regular basis you might get bad surprises, from all the kind of scripts that get executred. I am not one of these no-root paranoid. I am not scared of knives but I do not walk with a knife pointing at my chest on a crowded subway train.

 What I find unacceptable is that this guy is ignorant, has bad practices, dispenses bad suggestion, and does it with so much arrogance. No way!

From: raju at: 2010-04-07 07:21:55

I have compile linux kernel version 2.6.28 , when i see the " .ko " files after the kernel was compiled the size of the ".ko"  file is very large compared files created from the installation by cd . Is their any way to reduce the size .

I assume it has to do with the dependency  Cd installation manages this dependency than when we compile the kernel . Is there a way to reduce the the size of the kernel object files ? .

From: Manuel Schmitt at: 2012-04-02 13:23:20

Howto to compile kernel from scratch in German:

Linux Kernel neu bauen/nachbauen/compilieren (aus Vanilla-Sourcen)

From: at: 2006-11-06 02:59:33

You can also get root access by invoking:

sudo -s  

This eliminates the need to create a root accout.  However, either way works. 

 

From: at: 2007-03-05 06:04:11

I believe the command below was wrapped to two lines due to the cms software.  If I am not mistaken it should be one line unless you explicitly spit it using the "\" (backslash).

 For those new to the command line, note how the prompt changes for the second and third lines, indicating the command is continued across multiple lines:


 foo@foobar:~$ fakeroot make-kpkg --initrd --append-to-version=-custom \
> kernel_image \
> kernel_headers

From: at: 2008-04-04 10:24:26

And with make-kpkg, just set CONCURRENCY_LEVEL=X just before starting compilation to use multiple cores...

From: Anonymous at: 2008-12-04 20:27:13

I followed all of the instructions but I got a problem when I was building kernel:

scripts/mod/sumversion.c: In function ‘get_src_version’:
scripts/mod/sumversion.c:384: error: ‘PATH_MAX’ undeclared (first use in this function)
scripts/mod/sumversion.c:384: error: (Each undeclared identifier is reported only once
scripts/mod/sumversion.c:384: error: for each function it appears in.)
scripts/mod/sumversion.c:384: warning: unused variable ‘filelist’
make[3]: *** [scripts/mod/sumversion.o] Error 1
make[2]: *** [scripts/mod] Error 2
make[1]: *** [scripts] Error 2
make[1]: Leaving directory `/usr/src/linux-2.6.18'
make: *** [debian/stamp-build-kernel] Error 2

Any ideas?

From: Anonymous at: 2010-03-15 03:54:54

There is an error on version 2.6.33

,----
| COLUMNS=150 dpkg -l 'gcc*' perl dpkg 'libc6*' binutils make dpkg-dev |\
| awk '$1 ~ /[hi]i/ { printf("%s-%s\n", $2, $3) }'> debian/stamp/build/info
| uname -a >> debian/stamp/build/info
| echo using the compiler: >> debian/stamp/build/info
| grep LINUX_COMPILER include/linux/compile.h | \
| sed -e 's/.*LINUX_COMPILER "//' -e 's/"$//' >> debian/stamp/build/info
| grep: include/linux/compile.h: No such file or directory
| echo done > debian/stamp/build/kernel
| fakeroot /usr/bin/make -f ./debian/rules debian/stamp/binary/pre-linux-image-2.6.33-rc1-amd64
| make[1]: Entering directory `/usr/src/linux-2.6.33-rc1'
| ====== making target debian/stamp/install/linux-image-2.6.33-rc1-amd64 [new prereqs: ]======
| This is kernel package version 12.031.
| echo "The UTS Release version in include/linux/version.h"; echo " \"\" "; echo "does not match current version:"; echo " \"2.6.33-rc1-amd64\" "; echo "Please correct this."; exit 2
| The UTS Release version in include/linux/version.h
| ""
| does not match current version:
| "2.6.33-rc1-amd64"
| Please correct this.
| make[1]: *** [debian/stamp/install/linux-image-2.6.33-rc1-amd64] Error 2
`----

 

The solution

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=561569

 

Check this

From: Anonymous at: 2010-08-19 06:22:03

Same here.... btw, did you run the patches? for me it said, patch not found. could that be the problem?

From: Vincent at: 2011-02-08 11:55:40

I used a tip from  http://bugs.gentoo.org/show_bug.cgi?id=226169

"modifying linux-2.6.x/scripts/mod/sumversion.c, and adding #include <limits.h>
fixes this issue"

From: nevelis at: 2011-02-27 10:33:01

Shot, vincent :D that worked for me.

From: Anonymous at: 2009-04-17 13:32:45

thanks for the concurrency tip :) 25% utilization was kinda sad to watch :D

From: B3RG3R'NICOLAS at: 2008-12-06 17:17:45

(worked fine for me)

From: Morten at: 2009-03-01 22:40:29

Good summary on how to compile the kernel on ubuntu.

 I sometimes try out the latest test kernel from kernel.org, and after coping the systems current config file to .config I run

make oldconfig

That way I will be allowed to act on all new features of the newer kernel, something that is hidden to me when I run make menuconfig. After make oldconfig I can run make menuconfig as you describe.

From: KevinG at: 2010-04-29 23:30:36

Its worked for me. Thank YOU

From: Anonymous at: 2010-11-18 22:14:49

Hello, I'm almost new in Linux, but with the new kernel 2.6.35 available for my Ubuntu distro the old OSS is unchecked, and I need it for other applications. So, I must recompile a kernel with OSS API. I got the last kernel tarball downloaded (2.6.36). Following this HOWTO, I got this output when executing make-kpkg clean:

root@CORNEL-FS:/usr/src/linux# make-kpkg clean
exec make kpkg_version=12.033 -f /usr/share/kernel-package/ruleset/minimal.mk clean
====== making target minimal_clean [new prereqs: ]======
This is kernel package version 12.033.
test ! -f .config || cp -pf .config config.precious
test ! -e stamp-building || rm -f stamp-building
test ! -f Makefile || \
            make    ARCH=i386 distclean
make[1]: Entering directory `/usr/src/linux-headers-2.6.35-22-generic'
/usr/src/linux-headers-2.6.35-22-generic/ubuntu/aufs/Makefile:3: ubuntu/aufs/magic.mk: No such file or directory
make[3]: *** No rule to make target `ubuntu/aufs/magic.mk'.  Stop.
make[2]: *** [ubuntu/aufs] Error 2
make[1]: *** [_clean_ubuntu] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.35-22-generic'
make: *** [minimal_clean] Error 2

Why make is always returning to folder of 2.6.35.22-generic, when I'm already  running another kernel 2.6.35.7-custom downloaded from somewhere else? And while executing from "linux" directory? Any idea? Would be most thankful for it.

P.S. I'm having same problems when trying to compile something else...

From: tomba at: 2011-10-04 23:56:14

you should add info about initial ram disks (update-initramfs -c -k 'custname')

because this procedure doesn't create it by it self o.O

From: sid at: 2013-09-04 14:14:28

For example assume that I have installed 3.10.9 custom kernel now i would like to apply few patches and like to change it to 3.10.10.

How to achieve it ?