I still stick with xv6: https://github.com/mit-pdos/xv6-public https://github.com/mit-pdos/xv6-public - It's not only a kernel, but also have user space - Cod

I still stick with xv6: https://github.com/mit-pdos/xv6-public https://github.com/mit-pdos/xv6-public - It's not only a kernel, but also have user space - Code is pretty compact and well documented, in general can be understood in a few days - No need to spend hours to custom build gcc. Just use the one provided by the distro package manager The x86 version isn't mantained anymore. They switched to RISC-V.