Thanks for this, I enjoyed it. Just as a point of constructive criticism, I would say that you might want to go into some more detail on some of the pieces like how the linker script works, or how you are assembling your asm file. I took a look at the repo and figured it out pretty quickly, but I think a beginner would be pretty lost in some of those details.

Also, your buddy allocator fills me with shame. I didn't think of doing it that way when I wrote the physical memory allocator for my hobby OS, and my algorithm is way slow to initialize as a result of how I did it. I'm thinking I might have to go and revisit my allocator.