git push build kernel

April 2013
Kamal Mostafa <[email protected]>
Copyright 2022 Canonical Ltd.
Copyright (c) 2022 Krzysztof Kozlowski <[email protected]>

SPDX-License-Identifier: GPL-3.0-only

-------------------------------------

Automatic kernel build, just by pushing any branch (or tag or sha or ref)
to a special "branch name" on the build server.  Example:

                                     (this makes it go!) ----vvvvvvvvvvvvvv

    kamal@laptop:~/ubuntu-raring$ git push tangerine master:build-x86_64

    Total 0 (delta 0), reused 0 (delta 0)
    remote: building ... (ok to interrupt, build will continue) ...
    remote: git-build-kernel
    remote:        defconfig: defconfig
    remote:        arch: x86_64
    remote:        cc: ccache
    remote:   starting build in tangerine:/tmp/kernel-kamal-Um4LxEzU ...
    remote:   build log: tangerine:/tmp/kernel-kamal-Um4LxEzU/build.log
    remote:   elapsed: 00:00:11   load average: 0.30, 0.71, 1.32
    remote:   build completed OK. build log:
    remote:       tangerine:/tmp/kernel-kamal-Um4LxEzU/build.log
    To ssh:https://kamal@tangerine/home/kamal/src/linux/ubuntu-raring
     * [new branch]      master -> build-x86_64

The destination branch should be of format:
TARGET[-ARCH[-CONFIG]]

where:
 - TARGET, required, valid options: build|dt_binding_check|dtbs|dtbs_w1|dtbs_check|dtbs_check_w1
 - ARCH, optional, default: x86_64
 - CONFIG, optional, default: defconfig

Any local branch will work, so all of these are valid:

	git push tangerine master:build
	git push tangerine master:build-arm64
	git push tangerine master:build-riscv
	git push tangerine master:dt_binding_check-arm64
	git push tangerine master:dtbs_check-arm-qcom

	git push tangerine master-next:build-arm64-allyesconfig
	git push tangerine HEAD:build-arm-multi_v7
	git push tangerine HEAD:build-arm-multi_v7_defconfig

Features:
 - Ridiculously easy to use.
 - No locally installed tools required other than 'git'.
 - Works with a bare or a populated remote git repo.
 - Implements the standard proper fdr clean/build/binary-something sequence.
 - Constructs source packages in a chroot for improved reproducibility.
 - Can build multiple branches from the same repo simultaneously.
 - Builds are done on /tmp, so be sure it is tmpfs and you have a lot of RAM,
   for best experience.
   After the build, logs are left in /tmp, but no build output/binaries.
 - Recognized cross-compile architectures:
   x86_64, i386, alpha, arm, arm64, m68k, mips, powerpc, powerpc64, riscv,
   s390, sparc

Notes:
 - The 'build-.*' branch you push to will get removed after the build
   so as to not junk up your remote repo.  Its always okay to just delete
   those branches manually too (i.e. if the build server reboots and leaves
   them).

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

To set up your git push auto-builder

1. On the build server, clone Linux kernel repo, go to .git/hooks/ directory,
   and create a symlink to the builder's post-receive script.  This
   post-receive MUST be created as a symlink (not a copy):

        git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        cd linux/.git/hooks/
	ln -s ~/git-build-kernel/post-receive .

2. On the build server, install necessary cross-compilers and tools (e.g.
   dtschema, yamllint).

3. Optionally, on the build server, setup cleanup script in crontab, e.g.:

	0 5 * * 1 ${HOME}/git-build-kernel/gbk-cleanup --age 7 --user "${LOGNAME}"

4. On your local machine, set up a git remote to point to your repo on the
   build server, e.g:

	git remote add tangerine \
		ssh:https://YOURUSERNAME@tangerine:~/linux

5. Try a push to one of the special branch names (above).  Enjoy!