Adding a proprietary kernel module to Talos OS

talos-kernel-stuff.md

Adding a proprietary kernel module to Talos OS

1. Patching and building the kernel image
   1. Clone the pkgs repository from Github and check out the revision corresponding to your version of Talos OS

      git clone https://github.com/talos-systems/pkgs pkgs && cd pkgs
      git checkout v0.8.0

   2. Clone the Linux kernel and check out the revision that pkgs uses (this can be found in kernel/kernel-prepare/pkg.yaml and it will be something like the following: https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-x.xx.x.tar.xz)

      git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git && cd linux
      git checkout v5.15

   3. Your module will need to be converted to be in-tree. The steps for this are different depending on the complexity of the module to port, but generally it would involve moving the module source code into the drivers tree and creating a new Makefile and Kconfig.
   4. Stage your changes in Git with git add -A.
   5. Run git diff --cached --no-prefix > foobar.patch to generate a patch from your changes.
   6. Copy this patch to kernel/kernel/patches in the pkgs repo.
   7. Add a patch line in the prepare segment of kernel/kernel/pkg.yaml:

      patch -p0 < /pkg/patches/foobar.patch

   8. Build the kernel image. Make sure you are logged in to ghcr.io before running this command, and you can change or omit PLATFORM depending on what you want to target.

      make kernel PLATFORM=linux/amd64 USERNAME=your-username PUSH=true

   9. Make a note of the image name the make command outputs.
2. Building the installer image
   1. Copy the following into a new Dockerfile:

      FROM scratch AS customization
      COPY --from=ghcr.io/your-username/kernel:<kernel version> /lib/modules /lib/modules
      
      FROM ghcr.io/talos-systems/installer:<talos version>
      COPY --from=ghcr.io/your-username/kernel:<kernel version> /boot/vmlinuz /usr/install/${TARGETARCH}/vmlinuz

   2. Run to build and push the installer:

      INSTALLER_VERSION=<talos version>
      IMAGE_NAME="ghcr.io/your-username/talos-installer:$INSTALLER_VERSION"
      DOCKER_BUILDKIT=0 docker build --build-arg RM="/lib/modules" -t "$IMAGE_NAME" . && docker push "$IMAGE_NAME"

3. Deploying to your cluster

   talosctl upgrade --image ghcr.io/your-username/talos-installer:<talos version> --preserve=true