2 * fixmap.h: compile-time virtual memory allocation
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
8 * Copyright (C) 1998 Ingo Molnar
10 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
16 #include <asm/pgtable.h>
18 #include <linux/threads.h>
19 #include <asm/kmap_types.h>
23 * Here we define all the compile-time 'special' virtual
24 * addresses. The point is to have a constant address at
25 * compile time, but to set the physical address only
26 * in the boot process. We allocate these special addresses
27 * from the end of the consistent memory region backwards.
28 * Also this lets us do fail-safe vmalloc(), we
29 * can guarantee that these special addresses and
30 * vmalloc()-ed addresses never overlap.
32 * these 'compile-time allocated' memory buffers are
33 * fixed-size 4k pages. (or larger if used with an increment
34 * higher than 1) use fixmap_set(idx,phys) to associate
35 * physical memory with fixmap indices.
37 enum fixed_addresses {
39 /* reserved pte's for temporary kernel mappings */
41 FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
43 __end_of_fixed_addresses
46 #define FIXADDR_TOP (VMALLOC_START - PAGE_SIZE)
47 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
48 #define FIXADDR_START ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
50 #include <asm-generic/fixmap.h>
52 #define kmap_get_fixmap_pte(vaddr) \
54 pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \