fc-kernels

Overview

This project automates the building of custom Linux kernels for Firecracker microVMs, using the same kernel sources as official Firecracker repo and custom configuration files. It supports building specific kernel versions and uploading the resulting binaries to a Google Cloud Storage (GCS) bucket.

Prerequisites

• Linux environment (for building kernels)

Building Kernels

1. Configure kernel versions:

   • Edit kernel_versions.txt to specify which kernel versions to build (one per line, e.g., 6.1.102).
   • Place the corresponding config file in configs/ (e.g., configs/6.1.102.config).

2. Build:

   make build
   # or directly
   ./build.sh

   The built kernels will be placed in builds/vmlinux-<version>/<arch>/vmlinux.bin where <arch> is amd64 or arm64 (Go/OCI convention). For x86_64 backward compatibility, a legacy copy is also placed at builds/vmlinux-<version>/vmlinux.bin.

Development Workflow

• On every push, GitHub Actions will automatically build the kernels and save it as an artifact.

Architecture naming

Output directories use Go's runtime.GOARCH convention (amd64, arm64) so they match the infra orchestrator's TargetArch() path resolution. The build-time variable TARGET_ARCH (x86_64, arm64) is only used internally for config paths and cross-compilation flags.

New Kernel in E2B's infra

Note: these steps should give you new kernel on your self-hosted E2B using https://github.com/e2b-dev/infra

• Copy the kernel build in your project's object storage under e2b-*-fc-kernels
• In packages/api/internal/cfg/model.go update DefaultKernelVersion
• Build and deploy api

License

This project is licensed under the Apache License 2.0. See LICENSE for details.