The builder provides firecracker-compatible images for 2 kernel versions, 5.10.x and 4.19.x, and cloudhypervisor-compatible images for 1 kernel version, 5.12.

These images are extremely minimal. kernel-bin is built from SCRATCH and only contains a kernel binary. kernel-modules, also built from SCRATCH, only contains modules for that kernel.

Image files can be found in kernel/. The full chain of images which go into creating the eventually used bin and module images is:

• kernel/builder - Built from Ubuntu 20.04, installs packages required to build kernels.
• kernel/firecracker/base - Built from the builder image, compiles the kernel and modules from kernel/firecracker/configs. This image can be used in specs for versions older than Flintlock 0.5.0 and CAPMVM which do not support the separate bin and module images.
• kernel/cloud-hypervisor/base - Built from the builder image, compiles the kernel and modules from kernel/cloud-hypervisor/configs.
• kernel/bin - Built from either the firecracker or cloud-hypervisor base, contains only the kernel binary.
• kernel/modules - Built from either the firecracker or cloud-hypervisor base, contains only the kernel modules.

The resulting images can be added to Microvm specs like so:

ghcr.io/weaveworks-liquidmetal/firecracker-kernel-bin:X.X.X
ghcr.io/weaveworks-liquidmetal/firecracker-kernel-modules:X.X.X

ghcr.io/weaveworks-liquidmetal/cloudhypervisor-kernel-bin:X.X.X
ghcr.io/weaveworks-liquidmetal/cloudhypervisor-kernel-modules:X.X.X

For platforms using versions older than Flintlock 0.5.0 and CAPMVM 0.8.0 use the following legacy image for firecracker microvms:

ghcr.io/weaveworks-liquidmetal/flintlock-kernel:X.X.X

Note the filename locations for each of the kernels:

• If using the firecracker kernel or kernel-bin, the value of filename should be bin/vmlinux
• If using the cloud-hypervisor kernel-bin, the value of filename should be bin/vmlinux.bin

New images are published automatically when merged to main by Github Actions. You should not need to manually publish new images to the ghcr account.

• Add a new kernel config file in kernel/<FC/CH>/configs following the naming pattern
• Update the list of FC_KERNEL_VERSIONS or CH_KERNEL_VERSIONS in kernel/Makefile
• Update the versions lists in .github/workflows/kernel-images.yml and .github/workflows/kernel-images-manual.yml
• Update any docs (like this one) with new version info
• Update the Liquid Metal docs with new version info
• Open a PR with your changes
• Merge once checks and reviews pass

Your new version will be automatically published.

Note that Firecracker only supports 5.10 and 4.19 kernels.

1. Fork this repo, clone your fork
2. cd into kernel
3. Edit the Dockerfile for the image you want to change. The build sequence is as follows:

   	graph TD;
   		builder-->fc-base;
   		builder-->ch-base;
   		fc-base-->fc-bin;
   		ch-base-->ch-bin;
   		fc-base-->fc-modules;
   		ch-base-->ch-modules;
   

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4. Set your image registry export REGISTRY=docker.io/foobar
5. If you only want to build one or a subset of kernel versions, set this with export FC_KERNEL_VERSIONS=5.10.77 or export CH_KERNEL_VERSIONS=5.12
6. Run make build-fc or make build-ch to build the images and make push-fc or make push-ch to push the images to your registry