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TheWSL2-Linux-Kernel repo contains the kernel source code andconfiguration files for theWSL2 kernel.

If you discover an issue relating to WSL or the WSL2 kernel, please report it ontheWSL GitHub project. It is not possible to report issues on theWSL2-Linux-Kernel project.

If you're able to determine that the bug is present in the upstream Linuxkernel, you may want to work directly with the upstream developers. Please notethat there are separate processes for reporting anormal bug andasecurity bug.

Is there a missing feature that you'd like to see? Please request it on theWSL GitHub project.

If you're able and interested in contributing kernel code for your featurerequest, we encourage you tosubmit the change upstream.

Instructions for building an x86_64 WSL2 kernel with an Ubuntu distribution using bash areas follows:

1. Install the build dependencies:
   $ sudo apt install build-essential flex bison dwarves libssl-dev libelf-dev cpio qemu-utils

2. Modify WSL2 kernel configs (optional):
   $ make menuconfig KCONFIG_CONFIG=Microsoft/config-wsl

3. Build the kernel using the WSL2 kernel configuration and put the modules in amodulesfolder under the current working directory:
   $ make KCONFIG_CONFIG=Microsoft/config-wsl && make INSTALL_MOD_PATH="$PWD/modules" modules_install

   You may wish to include-j$(nproc) on the firstmake command to build in parallel.

Then, you can use a provided script to create a VHDX containing the modules:$ sudo ./Microsoft/scripts/gen_modules_vhdx.sh "$PWD/modules" $(make -s kernelrelease) modules.vhdx

To save space, you can now delete the compilation artifacts:$ make clean && rm -r "$PWD/modules"

If you prefer, you can also build the modules VHDX manually as follows:

1. Calculate the modules size (plus 256MiB for slack):modules_size=$(du -bs "$PWD/modules" | awk '{print $1;}'); modules_size=$((modules_size + (256 * (1<<20))));

2. Create a blank image file for the modules:dd if=/dev/zero of="$PWD/modules.img" bs=1024 count=$((modules_size / 1024))

3. Setup filesystem and mount img file:lo_dev=$(sudo losetup --find --show "$PWD/modules.img") && sudo mkfs -t ext4 "$lo_dev" && mkdir "$PWD/modules_img" && sudo mount "$lo_dev" "$PWD/modules_img"

4. Copy over the modules, unmount the img now that we're done with it:sudo cp -r "$PWD/modules/lib/modules/$(make -s kernelrelease)"/* "$PWD/modules_img" && sudo umount "$PWD/modules_img"

5. Convert the img to VHDX:qemu-img convert -O vhdx "$PWD/modules.img" "$PWD/modules.vhdx"

6. Clean up:rm modules.img # optionally $PWD/modules dir and the now-empty $PWD_modules_img dir too

Please see the documentation on the.wslconfig configurationfile for information on using a custom built kernel.