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
80
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