blob: f8c8182f7f2e642a0326af17534c43d6fcd3fe8e [file] [log] [blame]
* 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
* 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 <>
#ifndef _ASM_HIGHMEM_H
#define _ASM_HIGHMEM_H
#ifdef __KERNEL__
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <asm/kmap_types.h>
/* undef for production */
/* declarations for highmem.c */
extern unsigned long highstart_pfn, highend_pfn;
extern pte_t *kmap_pte;
extern pgprot_t kmap_prot;
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 PKMAP_BASE (0xfe000000UL)
#define LAST_PKMAP 1024
#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);
* CONFIG_LIMITED_DMA is for systems with DMA limitations such as Momentum's
* Jaguar ATX. This option exploits the highmem code in the kernel so is
* always enabled together with CONFIG_HIGHMEM but at this time doesn't
* actually add highmem functionality.
* These are the default functions for the no-highmem case from
* <linux/highmem.h>
static inline void *kmap(struct page *page)
return page_address(page);
#define kunmap(page) do { (void) (page); } while (0)
static inline void *kmap_atomic(struct page *page, enum km_type type)
return page_address(page);
static inline void kunmap_atomic(void *kvaddr, enum km_type type)
#define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx))
#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
#define flush_cache_kmaps() do { } while (0)
#else /* LIMITED_DMA */
extern void *__kmap(struct page *page);
extern void __kunmap(struct page *page);
extern void *__kmap_atomic(struct page *page, enum km_type type);
extern void __kunmap_atomic(void *kvaddr, enum km_type type);
extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
extern struct page *__kmap_atomic_to_page(void *ptr);
#define kmap __kmap
#define kunmap __kunmap
#define kmap_atomic __kmap_atomic
#define kunmap_atomic __kunmap_atomic
#define kmap_atomic_to_page __kmap_atomic_to_page
#define flush_cache_kmaps() flush_cache_all()
#endif /* LIMITED_DMA */
#endif /* __KERNEL__ */
#endif /* _ASM_HIGHMEM_H */