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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-$(uname -r)

All of the Ubuntu Kernel source is maintained under git. The source for each release is maintained in its own git repository on kernel.ubuntu.com. These can be browsed in gitweb, the official Ubuntu trees are in the ubuntu/ directory. The Ubuntu Linux kernel git repository is located at git://kernel.ubuntu.com/ubuntu/ubuntu-<release>.git or http://kernel.ubuntu.com/git-repos/ubuntu/ubuntu-<release>.git. To obtain a local copy you can simply git clone the repository for the release you are interested in as below. The git command is part of the git-core package:

• git clone git://kernel.ubuntu.com/ubuntu/ubuntu-<release>.git

For example to obtain the maverick tree:

• git clone git://kernel.ubuntu.com/ubuntu/ubuntu-maverick.git

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. Note that once these two trees are tied together you cannot remove the virgin Linus tree without damage to the Ubuntu tree:

• git clone git://kernel.ubuntu.com/ubuntu/linux.git
  git clone --reference linux git://kernel.ubuntu.com/ubuntu/ubuntu-karmic.git
  git clone --reference linux git://kernel.ubuntu.com/ubuntu/ubuntu-maverick.git

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.

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 as below:

• $ git tag -l Ubuntu-*
  Ubuntu-2.6.27-7.10
  Ubuntu-2.6.27-7.11
  Ubuntu-2.6.27-7.12
  Ubuntu-2.6.27-7.13
  Ubuntu-2.6.27-7.14
  $

To look at the 2.6.27-7.13 version you can simply checkout a new branch pointing to that version:

• git checkout -b temp Ubuntu-2.6.27-7.13

You may then manipulate the release for example 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