WSL Kernel Build

This repository has been set up to run automatic kernel builds for the Windows Subsystem for Linux (WSL), specifically aiming to track down its issue microsoft/WSL#8696 / microsoft/WSL#6982.

We have a Dockerfile for a container to run the builds in. It has been set up according to the WSL Kernel build documentation. The built image is available on Docker Hub.

The WSL2-Linux-Kernel repository is contained here as a Git submodule. A pushed change to its revision triggers a workflow here building the kernel on this specific codebase, which then will be tagged and provided as a release. Since we're building upstream kernel versions, which do not include the WSL kernel config, we're using the WSL kernel config from thelinux-msft-5.4.91 tag for all builds.

We're trying to use git-bisect to find the commit introducing the beforementioned issue. Since the issue does not appear instantly, but needs some inconsistent time until it pops up, people are invited to help testing the built kernel images in their environments. Please follow carlfriedrich/wsl-kernel-build#1 in this repository for the progress of the bisection.

To use a custom kernel, add the following lines to your .wslconfig file:

[wsl2]
kernel=C:\\Path\\To\\Kernel\\bzImage-5.4.0-microsoft-standard-WSL2

The .wslconfig file is located in your %UserProfile% directory (usually something like C:\Users\your_user_name) and can be created if it does not exist. Afterwards, shut down WSL and restart it using either Command Promt or PowerShell:

wsl --shutdown
wsl

Verify that the configured kernel is used within WSL:

$ uname --kernel-release
5.4.0-microsoft-standard-WSL2

Please note that the kernel version string is formatted differently than the git tag it was created from due to the implementation of the kernel version.

Manual kernel build

In case you want to manually build a WSL kernel, you can do so as follows:

git clone https://github.com/microsoft/WSL2-Linux-Kernel.git
git checkout v5.4
git show linux-msft-5.4.91:Microsoft/config-wsl > .config
docker run --rm --hostname wsl-kernel-build \
    -u $(id -u ${USER}):$(id -g ${USER}) \
    -v $(pwd):/src \
    carlfriedrich/wsl-kernel-build \
    bash -c "make -j 32 CONFIG_LOCALVERSION_AUTO=y KCONFIG_CONFIG=.config"

If you want to build another version, make sure to clean the build tree before checking out a new version:

git reset HEAD --hard
git clean -dfx