The author describes their experience of porting FreeBSD 14 to run on the Firecracker VMM. They explain that Firecracker was created by Amazon to efficiently launch virtual machines with minimal overhead for their AWS Lambda platform. The author’s interest in porting FreeBSD to Firecracker was driven by their desire to speed up the FreeBSD boot process and make it more available in AWS. They faced various challenges during the process, such as addressing compatibility issues related to the PVH boot mode, Xen hypercalls, and device discovery. They also made optimizations to improve system performance. Overall, the author successfully managed to make FreeBSD work on Firecracker.
https://www.usenix.org/publications/loginonline/freebsd-firecracker