2 * highmem.h: virtual kernel memory mappings for high memory
4 * Used in CONFIG_HIGHMEM systems for memory pages which
5 * are not addressable by direct kernel virtual addresses.
7 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
8 * Gerhard.Wichert@pdb.siemens.de
11 * Redesigned the x86 32-bit VM architecture to deal with
12 * up to 16 Terrabyte physical memory. With current x86 CPUs
13 * we now support up to 64 Gigabytes physical RAM.
15 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
18 #ifndef _ASM_HIGHMEM_H
19 #define _ASM_HIGHMEM_H
23 #include <linux/interrupt.h>
24 #include <asm/kmap_types.h>
26 /* undef for production */
27 #define HIGHMEM_DEBUG 1
30 extern void *kmap_high(struct page *page, int nonblocking);
31 extern void kunmap_high(struct page *page);
33 /* declarations for highmem.c */
34 extern unsigned long highstart_pfn, highend_pfn;
36 extern pte_t *kmap_pte;
37 extern pgprot_t kmap_prot;
38 extern pte_t *pkmap_page_table;
40 /* This gets set in {srmmu,sun4c}_paging_init() */
41 extern unsigned long fix_kmap_begin;
43 /* Only used and set with srmmu? */
44 extern unsigned long pkmap_base;
46 extern void kmap_init(void) __init;
49 * Right now we initialize only a single pte table. It can be extended
50 * easily, subsequent pte tables have to be allocated in one physical
53 #define LAST_PKMAP 1024
55 #define LAST_PKMAP_MASK (LAST_PKMAP - 1)
56 #define PKMAP_NR(virt) ((virt - pkmap_base) >> PAGE_SHIFT)
57 #define PKMAP_ADDR(nr) (pkmap_base + ((nr) << PAGE_SHIFT))
59 /* in arch/sparc/mm/highmem.c */
60 void *kmap_atomic(struct page *page, enum km_type type);
61 void kunmap_atomic(void *kvaddr, enum km_type type);
63 #define kmap(page) __kmap(page, 0)
64 #define kmap_nonblock(page) __kmap(page, 1)
66 static inline void *__kmap(struct page *page, int nonblocking)
70 if (page < highmem_start_page)
71 return page_address(page);
72 return kmap_high(page, nonblocking);
75 static inline void kunmap(struct page *page)
79 if (page < highmem_start_page)
84 #endif /* __KERNEL__ */
86 #endif /* _ASM_HIGHMEM_H */