Kernel/Compile

Contents

  1. Disclaimer
    1. Reasons for compiling a custom kernel
    2. Reasons for NOT compiling a custom kernel
    3. What you'll need
    4. How to get the kernel source
    5. Modifying the source for your needs
    6. Building the kernel
    7. When it's done
    8. Other
    9. External information

Disclaimer

Building and using a custom kernel will make it very difficult to get support for your system. You will not be allowed to file bugs on the custom-built kernel (if you do, they will be Rejected without explanation).

If you have a commercial support contract with Ubuntu/Canonical, this will void such support.

Also note that this page describes how to do things for the Edgy (2.6.17) kernel and newer! Until this kernel source, we did not have any mechanisms in place that would allow people to build their own kernels easily. This was intentional.

This page does NOT describe how to build stock kernels from kernel.org. This is how to rebuild the actual Ubuntu kernel source.

Reasons for compiling a custom kernel

Reasons for NOT compiling a custom kernel

What you'll need

To start, you will need to install a few packages.

sudo apt-get install linux-kernel-devel fakeroot kernel-wedge kernel-package

This will install the compiler related packages and kernel packaging tools. It will also install the git-core package, which is the best way to interact with the Ubuntu kernel source.

How to get the kernel source

There are two ways to obtain the Ubuntu kernel source. The prefered way it to use git. Detailed instructions for using git can be found in the [Ubuntu]Kernel Git Guide.

The other way is to simply:

sudo apt-get install linux-source-2.6.17

However, this will almost always be out of date. Using git allows you to always stay in sync with the latest Ubuntu kernel source.

It seems that it is possible to use this information on 6.06 by running something similar to `apt-get source linux-image-2.6.15-26-386', which will give you kernel source along with the debian folder needed for this guide. However, I'm just a user, proceed with caution.
-- Simon80 2006-07-17 02:09:06

After testing it, I must warn you that this documentation doesn't work if you choose the sudo apt-get install linux-source-2.6.17 way.
-- OuattaraAziz 2007-02-17 21:02:06

Modifying the source for your needs

For most people, simply modifying the configs is enough. If you need to install a patch, read the instructions from the patch provider for how to apply.

The stock Ubuntu configs are located in debian/config/ARCH/ where ARCH is the architecture you are building for. In this directory are several files. The config file is the base for all targets in that architecture. Then there are several config.FLAVOUR files that contain options specific to that target. For example, here are the files for 2.6.17, i386:

$ ls -l debian/config/i386/
total 88
-rw-r--r-- 1 me me 62737 Jun 14 18:31 config
-rw-r--r-- 1 me me  1859 Jun 12 14:59 config.386
-rw-r--r-- 1 me me  1394 Jun 12 14:59 config.686
-rw-r--r-- 1 me me  1420 Jun 12 14:59 config.k7
-rw-r--r-- 1 me me  1519 Jun 12 14:59 config.server
-rw-r--r-- 1 me me  1867 Jun 12 14:59 config.server-bigiron

If you need to change a config option, simply modify the file that contains the option. If you modify just the config file, it will affect all targets for this architecture. If you modify one of the target files, it only affects that target.

After applying a patch, or adjusting the configs, it is always best to regenerate the config files to ensure they are consistent. There is a helper command for this. To regenerate all architectures run:

debian/rules updateconfigs

If you just want to update one architecture, run:

debian/bin/oldconfig ARCH

Building the kernel

To build the kernel(s) is very simple. Depending on your needs, you may want to build all the kernel targets, or just one specific to your system. However, you also want to make sure that you do not clash with the stock kernels.

Use this command to build all targets for the architecture you are buidling on:

AUTOBUILD=1 fakeroot debian/rules binary-debs

The AUTOBUILD environment variable triggers special features in the kernel build. First, it skips normal ABI checks (ABI is the binary compatibility). It can do this because it also creates a unique ABI ID. If you used a git repo, this unique ID is generated from the git HEAD SHA. If not, it is generated from the uuidgen program (which means every time you execute the debian/rules build, the UUID will be different!). Your packages will be named using this ID.

To build a specific target, use this command:

AUTOBUILD=1 fakeroot debian/rules binary-debs flavours=k7

This will only build the AMD k7 variant of the i386 architecture.

The debs are placed in ubuntu-2.6/debian/build.

When it's done

Now that the build is complete, you can install the generated debs using dpkg:

sudo dpkg -i linux-image-2.6.17-2-ef427c-k7_2.6.17-2.2_i386.deb
sudo dpkg -i linux-headers--2.6.17-2-ef427c-k7_2.6.17-2.2_i386.deb

If you use modules from linux-restricted-modules, you will need to recompile this against your new linux-headers package. Details on how to do this will be added later.

Other

How to compile a kernel module

External information

[WWW] http://www.howtoforge.com/kernel_compilation_ubuntu Compile a kernel from kernel.org source in Ubuntu


CategoryKernel

last edited 2007-03-09 14:28:12 by Geertpoels