Limmat config for kernel dev

This is my config for Limmat for kernel development.

Smoothly sharing & reusing configs is not a key design goal for Limmat (if you really want to share your config, it's probably time to invest in actual CI), and I haven't been very careful to ensure this config is hermetic; it might not "just work" on your system (see the annoyingly many setup steps below). But it should serve as a nice starting point and an illustration of Limmat's functionality.

TODO: I don't know if th virtme-ng stuff works on Ubuntu due to AppArmor issues. You can disable the relevant restrictions with sudo sysctl -w kernel.apparmor_restrict_unprivileged_unconfined=0; sudo sysctl -w kernel.apparmor_restrict_unprivileged_userns=0;.

What it does

For every commit:

• Build the kernel under some different configs.

• Build some kselftests.

• Run those kselftests in a VM using virtme-ng.

• Run some KUnit tests.

• Run checkpatch.pl and check for TODOs and stuff.

  If the commit has a Checkpatch-ignore footer, it configures checkpatch errors to ignore for that commit. For example Checkpatch-ignore: EMAIL_SUBJECT,COMPLEX_MACRO will disable checkpatch's title checking and rules about macro hackery for that commit.

Using on Debian

# TODO: does the packaged vng work here? I've only tested using my own local checkout.
sudo apt update
sudo apt install -y build-essential linux-source bc kmod cpio flex ccache \
    libncurses-dev libelf-dev libssl-dev dwarves bison qemu-system-x86 virtme-ng

export LIMMAT_CONFIG=$THIS_REPO/limmat.toml

# Download the rootfs used for QEMU testing. (or see below to build it yourself).
cd $(dirname $LIMMAT_CONFIG)/mkosi-rootfs/
wget https://github.com/bjackman/limmat-kernel/releases/download/v0.2/image.tar.zst
mkdir image && tar --use-compress-program=unzstd -xf image.tar.zst -C image

cd path/to/kernel/tree
limmat watch origin/master  # Assuming origin/master is your base branch.

Building rootfs for kselftest.

A pre-built version is provided in the releases. To build it youself:

(Tested on Ubuntu 24.04.1, with AppArmor restrictions disabled)

• sudo apt install ccache debian-archive-keyrying
• sudo apt install pipx && pipx ensurepath
• pipx install git+https://github.com/systemd/mkosi.git
• cd mkosi-rootfs; mkosi -f