These kernel OCI images contain the kernel binary (at /boot/vmlinux) and supporting modules (in /lib/modules)
for guest VMs ran by Ignite.
$ makeAll LTS versions starting from 4.14 and above are supported by the Ignite team. This means in practice:
- 4.14.x
- 4.19.x
- 5.4.x
- 5.10.x
We also publish stable channel kernels, but they are not the default.
- 5.14.x
The exact patch versions may be found in the Makefile. The available versions exist in the stable kernel git tree.
The kernel Makefile has an upgrade command that will generate patched kernel configs for each specific version in KERNEL_VERSIONS.
The linux kernel source code is checked out in a build container for each target version, and a resulting "olddefconfig" based on each Firecracker recommended base-config in the upstream/ directory is then output to the versioned/ directory.
Once make upgrade-% has produced a firecracker base-config for all KERNEL_VERSIONS, the resulting versioned configs are copied to the generated/ dir and are patched with ignite specific ./config-patches. These configs under generated/ are used for the matching kernel builds.
Run:
$ make upgradeafter you've upgraded the values in the Makefile.
Some options to the kernel are specifically important for making guest software work.
Please see: config-patches for what kernel configs we've changed. The base kernel config is the MicroVM-optimized config file from the Firecracker team. We're storing it in upstream/config-amd64. It's available online at firecracker/resources.