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 <linux/config.h>
17 #include <linux/kernel.h>
19 #include <asm/apicdef.h>
22 #include <linux/threads.h>
23 #include <asm/kmap_types.h>
27 * Here we define all the compile-time 'special' virtual
28 * addresses. The point is to have a constant address at
29 * compile time, but to set the physical address only
30 * in the boot process. We allocate these special addresses
31 * from the end of virtual memory (0xfffff000) backwards.
32 * Also this lets us do fail-safe vmalloc(), we
33 * can guarantee that these special addresses and
34 * vmalloc()-ed addresses never overlap.
36 * these 'compile-time allocated' memory buffers are
37 * fixed-size 4k pages. (or larger if used with an increment
38 * highger than 1) use fixmap_set(idx,phys) to associate
39 * physical memory with fixmap indices.
41 * TLB entries of such buffers will not be flushed across
46 * on UP currently we will have no trace of the fixmap mechanizm,
47 * no page table allocations, etc. This might change in the
48 * future, say framebuffers for the console driver(s) could be
51 enum fixed_addresses {
52 #ifdef CONFIG_X86_LOCAL_APIC
53 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
55 #ifdef CONFIG_X86_IO_APIC
57 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
59 #ifdef CONFIG_X86_VISWS_APIC
60 FIX_CO_CPU, /* Cobalt timer */
61 FIX_CO_APIC, /* Cobalt APIC Redirection Table */
62 FIX_LI_PCIA, /* Lithium PCI Bridge A */
63 FIX_LI_PCIB, /* Lithium PCI Bridge B */
65 #ifndef CONFIG_X86_F00F_WORKS_OK
68 #ifdef CONFIG_X86_SUMMIT
69 FIX_CYCLONE_TIMER, /*cyclone timer register*/
72 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
73 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
75 #ifdef CONFIG_ACPI_BOOT
77 FIX_ACPI_END = FIX_ACPI_BEGIN + FIX_ACPI_PAGES - 1,
79 __end_of_permanent_fixed_addresses,
80 /* temporary boot-time mappings, used before ioremap() is functional */
81 #define NR_FIX_BTMAPS 16
82 FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
83 FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS - 1,
84 __end_of_fixed_addresses
87 extern void __set_fixmap (enum fixed_addresses idx,
88 unsigned long phys, pgprot_t flags);
90 #define set_fixmap(idx, phys) \
91 __set_fixmap(idx, phys, PAGE_KERNEL)
93 * Some hardware wants to get fixmapped without caching.
95 #define set_fixmap_nocache(idx, phys) \
96 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
100 * Leave one empty page between vmalloc'ed areas and
101 * the start of the fixmap, and leave one page empty
102 * at the top of mem..
104 #define FIXADDR_TOP (0xffffe000UL)
105 #define __FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
106 #define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE)
108 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
110 extern void __this_fixmap_does_not_exist(void);
113 * 'index to address' translation. If anyone tries to use the idx
114 * directly without tranlation, we catch the bug with a NULL-deference
115 * kernel oops. Illegal ranges of incoming indices are caught too.
117 static inline unsigned long fix_to_virt(const unsigned int idx)
120 * this branch gets completely eliminated after inlining,
121 * except when someone tries to use fixaddr indices in an
122 * illegal way. (such as mixing up address types or using
123 * out-of-range indices).
125 * If it doesn't get removed, the linker will complain
126 * loudly with a reasonably clear error message..
128 if (idx >= __end_of_fixed_addresses)
129 __this_fixmap_does_not_exist();
131 return __fix_to_virt(idx);