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