did mirage OS implemented the linux kernel in OCaml?

Question

Is it true that mirage is a new implementation of unix kernel with OCaml instead of C? or is mirage implemented only a part of unix kernel in Ocaml?

Thanks.

Answer 1

MirageOS isn't an implementation of any UNIX system at all. MirageOS assembles OCaml (or other language, via FFI) libraries to provide similar services as a traditional kernel. Most of them are written mostly in OCaml with some C stubs, and don't provide similar interfaces to UNIX-y system calls.

There are a few libraries which are built to let a traditional operating system provide the functionality that an application might need in MirageOS (for example, reading a file or sending a network packet), but these libraries aren't reimplementations of the kernel. They're OCaml libraries which make traditional system calls to use the kernel running the userspace OCaml program.