include/asm-i386/highmem.h

   1 /*
   2  * highmem.h: virtual kernel memory mappings for high memory
   3  *
   4  * Used in CONFIG_HIGHMEM systems for memory pages which
   5  * are not addressable by direct kernel virtual addresses.
   6  *
   7  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
   8  *                    Gerhard.Wichert@pdb.siemens.de
   9  *
  10  *
  11  * Redesigned the x86 32-bit VM architecture to deal with
  12  * up to 16 Terabyte physical memory. With current x86 CPUs
  13  * we now support up to 64 Gigabytes physical RAM.
  14  *
  15  * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
  16  */
  17
  18 #ifndef _ASM_HIGHMEM_H
  19 #define _ASM_HIGHMEM_H
  20
  21 #ifdef __KERNEL__
  22
  23 #include <linux/interrupt.h>
  24 #include <linux/threads.h>
  25 #include <asm/kmap_types.h>
  26 #include <asm/tlbflush.h>
  27
  28 /* declarations for highmem.c */
  29 extern unsigned long highstart_pfn, highend_pfn;
  30
  31 extern pte_t *kmap_pte;
  32 extern pgprot_t kmap_prot;
  33 extern pte_t *pkmap_page_table;
  34
  35 /*
  36  * Right now we initialize only a single pte table. It can be extended
  37  * easily, subsequent pte tables have to be allocated in one physical
  38  * chunk of RAM.
  39  */
  40 #ifdef CONFIG_X86_PAE
  41 #define LAST_PKMAP 512
  42 #else
  43 #define LAST_PKMAP 1024
  44 #endif
  45 /*
  46  * Ordering is:
  47  *
  48  * FIXADDR_TOP
  49  *                      fixed_addresses
  50  * FIXADDR_START
  51  *                      temp fixed addresses
  52  * FIXADDR_BOOT_START
  53  *                      Persistent kmap area
  54  * PKMAP_BASE
  55  * VMALLOC_END
  56  *                      Vmalloc area
  57  * VMALLOC_START
  58  * high_memory
  59  */
  60 #define PKMAP_BASE ( (FIXADDR_BOOT_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK )
  61 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  62 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  63 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  64
  65 extern void * FASTCALL(kmap_high(struct page *page));
  66 extern void FASTCALL(kunmap_high(struct page *page));
  67
  68 void *kmap(struct page *page);
  69 void kunmap(struct page *page);
  70 void *kmap_atomic(struct page *page, enum km_type type);
  71 void kunmap_atomic(void *kvaddr, enum km_type type);
  72 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
  73 struct page *kmap_atomic_to_page(void *ptr);
  74
  75 #define flush_cache_kmaps()     do { } while (0)
  76
  77 #endif /* __KERNEL__ */
  78
  79 #endif /* _ASM_HIGHMEM_H */