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_types.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_TYPE_NR*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 pgtable_init() 74 */ 75 extern void fixrange_init(unsigned long start, unsigned long end, 76 pgd_t *pgd_base); 77 78 79 #endif 80