Builder for Ubuntu Mainline kernels

This container will build a mainline kernel from the Ubuntu source tree. By default the container will build binary packages which you can then install on your systems. You can optionally build a metapackage to track a build flavour, and major release of kernel (eg 5.12.x).

If you build the metapackage it will have a name like: linux-generic-5.12 and will depend on the version of 5.12.x you are building.

Alternatively it can build signed source packages for uploading to a PPA.

I upload my mainline kernels to these PPAs

Kernel Version	Series	PPA Link	Packages
mainline/stable	focal	lts-mainline PPA	lts-mainline Packages
mainline/stable	jammy	jammy-mainline PPA	lts-mainline Packages
longterm	focal	lts-mainline-longterm PPA	lts-mainline-longterm Packages

building the container

To build the container with docker you would use:

docker build -t <org>/<image>:<tag> -f Dockerfile.<series> .

I build and push the Jammy series image using:

docker build -t tuxinvader/jammy-mainline-builder:latest -f Dockerfile.jammy .
docker push tuxinvader/jammy-mainline-builder:latest

and focal with:

docker build -t tuxinvader/focal-mainline-builder:latest -f Dockerfile.focal .
docker push tuxinvader/focal-mainline-builder:latest

Usage

Checkout the Mainline kernel from Ubuntu

sudo mkdir -p /usr/local/src/cod/
sudo chown $(whoami) /usr/local/src/cod

Download the full source tree, if you want to be able to build any kernel (including previous releases)

git clone git://git.launchpad.net/~ubuntu-kernel-test/ubuntu/+source/linux/+git/mainline-crack \
/usr/local/src/cod/mainline

Download a specific kernel version if you only need to build this version. Eg v5.12.4:

git clone --depth=1 -b cod/mainline/v5.12.4 \
git://git.launchpad.net/~ubuntu-kernel-test/ubuntu/+source/linux/+git/mainline-crack \
/usr/local/src/cod/mainline

You should also pass --update=no when checking out only a single release.

Create a directory to receive the Debian packages
```
mkdir /usr/local/src/cod/debs
```
Run the container

Launch the container with two volume mounts, one to the source code downloaded above, and the other for the deb packages to be copied into.

Binary debs

sudo docker run -ti -e kver=v5.12.1 -v /usr/local/src/cod/mainline:/home/source \
     -v /usr/local/src/cod/debs:/home/debs --rm tuxinvader/focal-mainline-builder:latest

Go and make a nice cup-of-tea while your kernel is built.

If you want to build a signed source package, you need to also provide your GPG keyring:

Signed Source package

sudo docker run -ti -e kver=v5.12.1 -v /usr/local/src/cod/mainline:/home/source \
     -v /usr/local/src/cod/debs:/home/debs -v ~/.gnupg:/root/keys \
     --rm tuxinvader/focal-mainline-builder:latest --btype=source --sign=<SECRET_KEY_ID> \
     --flavour=generic --exclude=cloud-tools,udebs --rename=yes

Build and sign metapackage

sudo docker run -ti -e kver=v5.12.1 -v /usr/local/src/cod/mainline:/home/source \
     -v /usr/local/src/cod/debs:/home/debs -v ~/.gnupg:/root/keys \
     --rm tuxinvader/focal-mainline-builder:latest --btype=source --sign=<SECRET_KEY_ID> \
     --flavour=generic --exclude=cloud-tools,udebs --rename=yes --buildmeta=yes \
     --maintainer="Zaphod <zaphod@betelgeuse-seven.western-spiral-arm.milkyway>"

The Linux source package builds some debs which are linked (by name) against the kernel and some which are common. Using --rename=yes allows us to store multiple kernels in the same PPA by changing the name of the source package and the linking all binaries (by name) to a specific kernel.

Notes

Set the kver variable to the version of the kernel you want to build (from here: https://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D)

The built packages or source files will be placed in the mounted volume at /home/debs, which is /usr/local/src/cod/debs if you've followed the example.

The container will do an update in the source code repository when it runs, if the tree is already up-to-date then you can append --update=no to the docker run command to skip that step.

Flavour lowlatency removed

With kernel 5.16.12 the mainline kernel discontinued the lowlatency flavour. So, the default build now only builds the generic flavour on 5.16.12+. The build script has been updated to recreate lowlatency options, but only if you specify that with --flavour=lowlatency.

Additional options

Update: You can pass --update=[yes|no] to have the container perform a git pull before building the kernel. Default is yes
Shell: You can pass --shell=[yes|no] to launch a bash shell before and after the build process. Default is no
Build Type: You can pass --btype=[binary,source,any,all,full] to chose the type of build performed. Default is binary.
Customize: You can pass --custom=[yes|no] to run make menuconfig before the the build process. Default is no
Sign: You can pass --sign=<secret-key-id> to sign source packages ready for uploading to a PPA. Default is no. You'll also need to mount your GPG keys into the container. Eg: -v ~/.gnupg:/root/keys and specify --btype=source
Flavour: You can pass --flavour=[generic|lowlatency] if you want to select the build flavour. The default is none, and we build the generic flavour (since 5.16.12+).
Exclude: You can pass --exclude=[cloud-tools,udebs] to exclude one or more packages. Default is none.
Rename: You can pass --rename=[yes|no] to rename the source package to be kernel release specific. This enables hosting multiple kernels in the same PPA. Use with --exclude=tools,udebs to stop duplicate packages being built. Default is no
Series: You can pass --series=[focal|groovy|...] to set the ubuntu version you're building for. Default is jammy
Patch: You can pass a patch version to apply upstream patch to the ubuntu kernel. Eg --patch=v5.11.21 to patch v5.11.20 upto v5.11.21. Default is no
Check bugs: You can pass --checkbugs=yes to work around any known bugs, currently this is required to build older 5.10.x and 5.11.x kernels see bug #4
Maintainer: If you want to sign the metapackage (for PPA upload), then you need to provide the details of your signing key by passing --maintainer="Me <me@mine.org>"
Debug Symbols: If you want to package a version of the kernel which includes debug-symbols, then pass --debug=yes to the binary build.
Build metapackage: You can pass --buildmeta=[yes|no] to build a metapackage named linux-<flavour>-<major version> that will depend on the kernel you are building. This makes it easy to track the latest release and auto-update using apt.
Meta Only: You can decide to just rebuild the metapackage by passing --metaonly=yes, useful for rolling back a release should it fail to build. This needs to be combined with --buildmeta=yes.
Meta Time: The source (orig.tar.gz) tarball is immutable on launchpad, so we need to ensure the ordering, contents, and modification times match on every build. The timestamp defaults to "2023-01-01 00:00:00", but you can override it with --metatime=<epoch-seconds>
Meta Version: We now append -n to meta-packages so that we can republish/rebuild them on launchpad by incrementing the version. You also need to ensure the metatime is consistent, else the orig.tar.gz will be rejected. The version defaults to 0, eg linux 6.1.0 would be linux-generic-6.01_6.1.0-0, passing --metaver=1 would result in linux-generic-6.01_6.1.0-1
Have Rust: Build a kernel with rust support? The haverust flag defaults to no on focal and yes on other releases. Currently building on jammy requires --haverust=no because bindgen-0.56 is unavailable. See this Ubuntu backport bug

TuxInvader / focal-mainline-builder