Ubuntu Wiki

The literal source code which generated a specific binary package may be obtained using the apt-get source <package> command. For example to obtain the source for the currently running kernel you can use the command below:

• apt-get source linux-image-unsigned-$(uname -r)

or failing that:

• apt-get source linux-image-$(uname -r)

The source for each release is maintained in its own git repository on Launchpad.

The git repository is listed in the Vcs-Git: header in the source package and is of the following form:

• git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/<source package>/+git/<series>

For example, the standard Jammy kernel is available at:

• git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy

There is a tree for each of the currently supported releases as well as any open development and upcoming releases. For example:

• focal	git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal
  jammy	git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy
  noble	git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/noble

Replace your intended Ubuntu series in the above URL, and pull the source for the kernels you need.

The distro kernel is always on the master branch in these repositories. Each release also has a master-next branch containing the commits that will go into the master branch and become the next SRU release for that series.

A number of releases also have other source packages which represent other related but divergent kernels for other purposes. For example, there is a specialized AWS kernel available in the linux-aws source package. (Previously these sorts of things were done in Topic Branches and some older kernels and projects still use them.)

If you cannot use the git protocol (perhaps because of a firewall), you can use the slower https protocol. For example:

• jammy	https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy
  noble	https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/noble

Obtaining a copy

To obtain a local copy you can simply git clone the repository for the release you are interested in. The git command is part of the git package.

For example to obtain the Jammy tree:

• git clone git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy

This will download several hundred megabytes of data. If you plan on working on more than one kernel release you can save space and time by downloading the upstream kernel tree, and use it as a reference. Note that once these two trees are tied together you cannot simply delete or move the virgin Linus tree without manually updating .git/objects/info/alternates in your Ubuntu kernel tree:

• git clone git://kernel.ubuntu.com/ubuntu/linux.git
  git clone --reference linux git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy
  git clone --reference linux git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/noble

In each case you will end up with a new directory <ubuntu-release> containing the source and the full history which can be manipulated using the git command from within each directory.

If you are an advanced git user, you can also add each Ubuntu series as a remote so that you can have all kernel series you need in a single directory. For example,

• git remote add jammy git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy
  git fetch jammy
  git checkout -b jammy --track jammy/master
  git checkout -b jammy-next --track jammy/master-next

By default you will have the latest version of the kernel tree, the master tree. You can switch to any previously released kernel version using the release tags. To obtain a full list of the tagged versions in the release, use the git tag command below:

• $ git tag -l Ubuntu-*
  Ubuntu-5.4.0-47.51
  Ubuntu-5.4.0-48.52
  Ubuntu-5.4.0-49.53
  Ubuntu-5.4.0-51.56
  Ubuntu-5.4.0-52.57
  ...

To look at the Ubuntu-5.4.0-52.57 version you can simply checkout a new branch pointing to that version:

• git checkout -b temp Ubuntu-5.4.0-52.57

You may then manipulate the release - for example, by adding new commits.

A common set of tools used by the kernel team are maintained in a git repository.

• buildscripts: Scripts used to farm out the kernel builds to very fast remote
• chroot-setup: Scripts to setup jailed kernel compilation enviroments.
• daily-test-isos: Scripts and support files to produce daily, custom test isos.
• git-hooks: Optional hooks to help you commit patches
• maintscripts: Scripts used for general / stable kernel maintenance
• mainline-build: Scripts to produce .debs for mainline kernels
• misc: Everything else...

Download them using the following command.

git clone git://kernel.ubuntu.com/ubuntu/kteam-tools.git kteam-tools

To automatically create the chroot environment use:

chroot-setup/make_chroot <suite> <arch> [<mirror>]

For example:

sudo mkdir -p /usr3/chroots # prep environment
sudo chroot-setup/make_chroot precise amd64  http://archive.ubuntu.com/ubuntu

Where:

• arch stands for different arch supported by the CPU, for example i386 on AMD64 or LPIA on i386 etc.
• suite stands for release name such as hardy, gutsy, intrepid etc.

• mirror stands for the http location to download environment from, http://host[:port]/dir/

Note: You don't need to specify a mirror when using the LPIA arch