Walleij: ARM32 page tables

Linus Walleij continues his series of blog posts on the 32-bit Arm kernelwith thisdetailed description about how page tables work. "The Linuxkernel will act as if 5 levels of page tables exist. This is of coursegrossly over-engineered for ARM32 which has 2 or 3 levels of page tables,but we need to cater for the rest of the world. One size fits all. Inpractice, the code is organized such that these page tables 'fold' and wemostly skip over the intermediate translation steps when possible."