Update
Only follow this post if you need kernel 6.6. If you plan on playing with cilium/eBPF or you don’t need any specific feature from newer kernel go with 5.15.x.
I’ve created tutorial on that here
Introduction
A few days ago, I wanted to update my linux kernel running under WSL to a newer 6.x version, because I saw they have already published 6.6.36.6 on their microsoft WSL2 github and I was running just 5.15.x.
But even after spamming update button and enabling all updates for all products I still wouldnt get 6.x. This is because it apparently takes time until they move this release to microsoft update catalog , which ends with the 5.10.102.2 version at the time of this writing.
Disclaimer
Due to config changes that happened in the WSL2 kernel release 6.6.x, some of the configs Docker requires were changed to be loadable modules instead of their previously built-in state.
If you don’t add these changes, the docker won’t work with WSL2.
How to
We can run everything in the docker container to make it clean.
Create script with the following content
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vim build.sh
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WSL_COMMIT_REF=linux-msft-wsl-6.6.36.6
apt update && apt install -y git build-essential flex bison libssl-dev libelf-dev bc python3 cpio dwarves curl vim
mkdir src
cd src
git init
git remote add origin https://github.com/microsoft/WSL2-Linux-Kernel.git
git config --local gc.auto 0
git -c protocol.version=2 fetch --no-tags --prune --progress --no-recurse-submodules --depth=1 origin +${WSL_COMMIT_REF}:refs/remotes/origin/build/linux-msft-wsl-6.6.y
git checkout --progress --force -B build/linux-msft-wsl-6.6.y refs/remotes/origin/build/linux-msft-wsl-6.6.y
#download edited wsl-config with all the changes required for docker to run
curl -o /src/Microsoft/config-wsl https://blog.thetechcorner.sk/assets/text/config-wsl
# build the kernel
echo -ne '\n' | make -j$(nproc) KCONFIG_CONFIG=Microsoft/config-wsl
#copy the files from container
rm -rf .git
cp -r /src /output
Run the container with the script
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docker run --name wsl2-build --rm -it -v $PWD/output/:/output/ -v $PWD/build.sh:/build.sh ubuntu:22.04 bash -c "./build.sh"
The credit for config-wsl goes to @eapotapov, which kindly shared it on already mentioned github issue.
Copy the image to /mnt/c
Create a directory for kernels on Windows filesystem
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cd output/src
cp arch/x86/boot/bzImage /mnt/c/Users/<your-user>/bzImage
Edit WSL config
Edit WSL config so it, uses our freshly compiled kernel. Keep the double slashes.
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C:\Users\something\.wslconfig
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[wsl2]
kernel=C:\\Users\\<your-user>\\bzImage
Restart WSL
From the powershell of your PC shutdown the WSL
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#shutdown
wsl --shutdown
#start again
wsl
Check your new kernel
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uname -r
And you should see 6.6.x like so
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6.6.36.6-microsoft-standard-WSL2+