As you might be aware of, I am working on a minimal BSD/UNIX system called smolBSD. It is based on the NetBSD operating system, and its main target is virtual machines, more specifically microvms. This system is capable of fully booting the OS in less than one second using a specially trimmed kernel along with small, specialized root systems.
I was stunned to learn (but am I wrong?) that this work does not seem to have an equivalent, not even in the Linux world. FreeBSD Firecracker support sure permits to boot a kernel is about the same time my NetBSD hacked kernel does, but there’s no work around s slim and task dedicated root filesystem.
Microvm
In November 2018 AWS published an Open Source tool called Firecracker, mostly a virtual machine monitor relying on KVM, a small sized Linux kernel, and a stripped down version of Qemu. What baffled me was the speed at which the virtual machine would fire up and run the service. The whole process is to be compared to a container, but safer, as it does not share the kernel nor any resource, it is a separate and dedicated virtual machine.
If you want to learn more on Firecracker’s internals, here’s a very well put article.