== Obtaining the kernel sources for an Ubuntu release using git ==

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 [[KernelTeam/TopicBranches|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.