void init_mmu (void)
Sets up the processor for virtual addressing mode by setting up page-mapping hardware and enabling the pager.
On the x86 family, it sets up the page tables as well as special mappings to "known" physical address ranges (e.g. sets up a virtual address for the physical address ranges 0 through 0xFFFFF inclusive).
On the ARM family, this function simply sets up the page tables.