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/config.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/threads.h>
  26 #include <asm/kmap_types.h>
  27 #include <asm/tlbflush.h>
  28
  29 /* declarations for highmem.c */
  30 extern unsigned long highstart_pfn, highend_pfn;
  31
  32 extern pte_t *kmap_pte;
  33 extern pgprot_t kmap_prot;
  34 extern pte_t *pkmap_page_table;
  35
  36 extern void kmap_init(void);
  37
  38 /*
  39  * Right now we initialize only a single pte table. It can be extended
  40  * easily, subsequent pte tables have to be allocated in one physical
  41  * chunk of RAM.
  42  */
  43 #if NR_CPUS <= 32
  44 #define PKMAP_BASE (0xff800000UL)
  45 #else
  46 #define PKMAP_BASE (0xff600000UL)
  47 #endif
  48 #ifdef CONFIG_X86_PAE
  49 #define LAST_PKMAP 512
  50 #else
  51 #define LAST_PKMAP 1024
  52 #endif
  53 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  54 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  55 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  56
  57 extern void * FASTCALL(kmap_high(struct page *page));
  58 extern void FASTCALL(kunmap_high(struct page *page));
  59
  60 void *kmap(struct page *page);
  61 void kunmap(struct page *page);
  62 void *kmap_atomic(struct page *page, enum km_type type);
  63 void kunmap_atomic(void *kvaddr, enum km_type type);
  64 struct page *kmap_atomic_to_page(void *ptr);
  65
  66 #define flush_cache_kmaps()     do { } while (0)
  67
  68 #endif /* __KERNEL__ */
  69
  70 #endif /* _ASM_HIGHMEM_H */