#pragma once

// Kernel mappings that are neither the direct map nor plain device registers.
// Both take one 1 GB slot of the device window ioremap() hands out, so each is
// limited to a gigabyte and meant to be called a handful of times at boot.

// Program this CPU's PAT so that a mapping can ask for write-combining. Every
// CPU runs it before it touches a write-combined mapping -- the PAT is per
// processor, and one left at its reset value reads the same bits as
// write-back, which on device memory the MTRRs then turn back into uncached.
void  pat_init(void);

// Device memory, write-combined: stores are gathered into bursts rather than
// sent one at a time, and reads are as slow as uncached. For a framebuffer,
// never for registers. Returns 0 if there is no window left.
void *ioremap_wc(uint64 pa, uint64 size);

// `size` bytes of ordinary RAM, contiguous in the kernel's address space and
// not physically: kalloc() pages behind a page table of their own. Zeroed.
// For buffers too big for the DMA arena that no device reads. Never freed.
void *vmap_alloc(uint64 size);