Module memory 

Memory Layout

Constants

HHDM_BASE

A simple Higher Half Direct Map (HHDM) base. Anything you map at HHDM_BASE + pa lets the kernel access physical memory via a fixed offset.

IDENTITY_LOW_BYTES

Keep a tiny identity map so the paging switch code remains executable right after CR3 reload (and to let you pass low pointers if you want).

KERNEL_BASE

Where the kernel executes (VMA), matches your linker script.

PHYS_LOAD

Where you place the bytes in physical memory (LMA) before paging.