arch/mips/include/asm/fixmap.h

   1 /*
   2  * fixmap.h: compile-time virtual memory allocation
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 1998 Ingo Molnar
   9  *
  10  * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
  11  */
  12
  13 #ifndef _ASM_FIXMAP_H
  14 #define _ASM_FIXMAP_H
  15
  16 #include <asm/page.h>
  17 #include <spaces.h>
  18 #ifdef CONFIG_HIGHMEM
  19 #include <linux/threads.h>
  20 #include <asm/kmap_size.h>
  21 #endif
  22
  23 /*
  24  * Here we define all the compile-time 'special' virtual
  25  * addresses. The point is to have a constant address at
  26  * compile time, but to set the physical address only
  27  * in the boot process. We allocate these special  addresses
  28  * from the end of virtual memory (0xfffff000) backwards.
  29  * Also this lets us do fail-safe vmalloc(), we
  30  * can guarantee that these special addresses and
  31  * vmalloc()-ed addresses never overlap.
  32  *
  33  * these 'compile-time allocated' memory buffers are
  34  * fixed-size 4k pages. (or larger if used with an increment
  35  * highger than 1) use fixmap_set(idx,phys) to associate
  36  * physical memory with fixmap indices.
  37  *
  38  * TLB entries of such buffers will not be flushed across
  39  * task switches.
  40  */
  41
  42 /*
  43  * on UP currently we will have no trace of the fixmap mechanizm,
  44  * no page table allocations, etc. This might change in the
  45  * future, say framebuffers for the console driver(s) could be
  46  * fix-mapped?
  47  */
  48 enum fixed_addresses {
  49 #define FIX_N_COLOURS 8
  50         FIX_CMAP_BEGIN,
  51         FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * 2),
  52 #ifdef CONFIG_HIGHMEM
  53         /* reserved pte's for temporary kernel mappings */
  54         FIX_KMAP_BEGIN = FIX_CMAP_END + 1,
  55         FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_MAX_IDX * NR_CPUS) - 1,
  56 #endif
  57         __end_of_fixed_addresses
  58 };
  59
  60 /*
  61  * used by vmalloc.c.
  62  *
  63  * Leave one empty page between vmalloc'ed areas and
  64  * the start of the fixmap, and leave one page empty
  65  * at the top of mem..
  66  */
  67 #define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  68 #define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)
  69
  70 #include <asm-generic/fixmap.h>
  71
  72 /*
  73  * Called from pagetable_init()
  74  */
  75 extern void fixrange_init(unsigned long start, unsigned long end,
  76         pgd_t *pgd_base);
  77
  78
  79 #endif