xv6 might be nicer start: https://pdos.csail.mit.edu/6.828/2012/xv6.html https://pdos.csail.mit.edu/6.828/2012/xv6.html For bootstrapping, the overall consens

xv6 might be nicer start: https://pdos.csail.mit.edu/6.828/2012/xv6.html https://pdos.csail.mit.edu/6.828/2012/xv6.html For bootstrapping, the overall consensus is you make enough C to compile, without optimizations, early version of GCC which compiles itself from there until you reach current version. Several folks are trying to compile TCC instead to leverage it and dwheeler's work.