1. 根目录:
2. arch
3. mips
4. include
5. asm
6. highmem.h

/*
 * highmem.h: virtual kernel memory mappings for high memory
 *
 * Used in CONFIG_HIGHMEM systems for memory pages which
 * are not addressable by direct kernel virtual addresses.
 *
 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
 *		      Gerhard.Wichert@pdb.siemens.de
 *
 *
 * Redesigned the x86 32-bit VM architecture to deal with
 * up to 16 Terabyte physical memory. With current x86 CPUs
 * we now support up to 64 Gigabytes physical RAM.
 *
 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
 */
#ifndef _ASM_HIGHMEM_H
#define _ASM_HIGHMEM_H

#ifdef __KERNEL__

#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <asm/kmap_types.h>

/* undef for production */
#define HIGHMEM_DEBUG 1

/* declarations for highmem.c */
extern unsigned long highstart_pfn, highend_pfn;

extern pte_t *pkmap_page_table;

/*
 * Right now we initialize only a single pte table. It can be extended
 * easily, subsequent pte tables have to be allocated in one physical
 * chunk of RAM.
 */
#define LAST_PKMAP 1024
#define LAST_PKMAP_MASK (LAST_PKMAP-1)
#define PKMAP_NR(virt)	((virt-PKMAP_BASE) >> PAGE_SHIFT)
#define PKMAP_ADDR(nr)	(PKMAP_BASE + ((nr) << PAGE_SHIFT))

extern void * kmap_high(struct page *page);
extern void kunmap_high(struct page *page);

extern void *kmap(struct page *page);
extern void kunmap(struct page *page);
extern void *kmap_atomic(struct page *page);
extern void __kunmap_atomic(void *kvaddr);
extern void *kmap_atomic_pfn(unsigned long pfn);

#define flush_cache_kmaps()	flush_cache_all()

extern void kmap_init(void);

#define kmap_prot PAGE_KERNEL

#endif /* __KERNEL__ */

#endif /* _ASM_HIGHMEM_H */