I agree, this is really just a "how to boot x86" rather than an actual kernel. But then, they're just using GRUB to boot into 32-bit (Which is the best way to d

I agree, this is really just a "how to boot x86" rather than an actual kernel. But then, they're just using GRUB to boot into 32-bit (Which is the best way to do it) which means their "kernel" does basically nothing - they're just writing to 0xB8000. I second xv6, it's a bit simplistic, and not the cleanest, but it really shows the basics of a 'real' kernel - locking and task scheduling, a basic file-system and block layer, some userspace utilities, and fantastic documentation (There's a whole book!).