If you're looking for a Unix-like, POSIX-compatible, real-time kernel, there's no shortage of projects trying to build one. Ironclad stands out for using the Ada programming language and its formally ...
If you read Japanese, you might have seen the book “Design and Implementation of Microkernels” by [Seiya Nuda]. An appendix covers how to write your own operating system for RISC-V in about 1,000 ...