I know XNU K32 is running in 32-bit. But which 32-bit mode is it in, protect-mode or IA32e-compatibility-mode? In the protect-mode, the MMU takes 32-bit cr3 and using two-level page directories. In the compatibilty-mode, MMU takes 64-bit cr3 and using four-level page directories. I know the kernel has its own cr3 setting separated from any user space processes but I do not know which mode it uses to setup the cr3 and the page directories.