WSL2 Kernel Build Script

Build a custom Microsoft WSL2 kernel from source, then generate a matching Windows .wslconfig file. The project is intended for Debian or Ubuntu environments running inside WSL2.

What Changed

• The build script now uses strict bash settings, safer temp directory handling, and a local .wslconfig generator instead of executing a remote script.
• Kernel version discovery now uses git ls-remote against the upstream Microsoft repository, not brittle HTML parsing and not the GitHub API.
• The .wslconfig generator now validates inputs, detects Windows hardware from PowerShell, and writes current settings into the correct [wsl2] and [experimental] sections.
• A config-wsl file with full CAN bus support is bundled in the repo and is used automatically by build-kernel.sh (override with --config <path>).
• CI, linting, smoke tests, and basic repo hygiene files have been added.

Requirements

• WSL2 on Windows with a Debian or Ubuntu distro
• sudo access inside the distro
• Internet access to download the upstream kernel source

The build script installs missing packages automatically with apt-get.

Usage

Clone the repository and run the build:

git clone https://github.com/slyfox1186/wsl2-kernel-build-script.git
cd wsl2-kernel-build-script
sudo bash build-kernel.sh

Build a specific version:

sudo bash build-kernel.sh --version 6.6.87.2 --output-directory "$HOME/WSL2"

Build the latest kernel from a major series:

sudo bash build-kernel.sh --series 6 --skip-wslconfig

List upstream versions:

bash build-kernel.sh --list-versions

Generate only .wslconfig:

bash wslconfig-generator.sh --kernel /mnt/c/Users/you/WSL2/vmlinux

Kernel configuration

The repo ships a config-wsl file with full Linux CAN bus support enabled (raw, BCM, GW, J1939, ISO-TP, vcan, vxcan, plus the common controller and USB drivers). When build-kernel.sh runs, it picks the kernel .config in this order:

1. --config <path> if you pass one explicitly.
2. The repo's config-wsl if it exists alongside build-kernel.sh.
3. Upstream Microsoft/config-wsl from the kernel source tarball.

make olddefconfig is then run inside the kernel tree, so any options new to the kernel version you build will be initialized to their defaults without prompting.

To use your own config, point at it:

sudo bash build-kernel.sh --config /path/to/my-config-wsl

To force the upstream Microsoft default instead of the bundled config, rename or delete config-wsl in the repo before running the script.

Output

The kernel build produces vmlinux in your selected output directory. Store that file somewhere stable on Windows, for example:

C:\Users\<your-user>\WSL2\vmlinux

Create C:\Users\<your-user>\.wslconfig and point kernel= at that file. A sample config lives at .wslconfig.example.

After updating the Windows config, apply the change from PowerShell or Command Prompt:

wsl --shutdown

Development

Run the local checks before pushing changes:

make lint
make smoke

References

• Microsoft WSL2 kernel source: https://github.com/microsoft/WSL2-Linux-Kernel/
• Microsoft WSL configuration docs: https://learn.microsoft.com/windows/wsl/wsl-config