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highmem.h
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1 /*
2  * highmem.h: virtual kernel memory mappings for high memory
3  *
4  * Used in CONFIG_HIGHMEM systems for memory pages which
5  * are not addressable by direct kernel virtual addresses.
6  *
7  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
9  *
10  *
11  * Redesigned the x86 32-bit VM architecture to deal with
12  * up to 16 Terabyte physical memory. With current x86 CPUs
13  * we now support up to 64 Gigabytes physical RAM.
14  *
15  * Copyright (C) 1999 Ingo Molnar <[email protected]>
16  */
17 #ifndef _ASM_HIGHMEM_H
18 #define _ASM_HIGHMEM_H
19 
20 #ifdef __KERNEL__
21 
22 #include <linux/init.h>
23 #include <linux/interrupt.h>
24 #include <linux/uaccess.h>
25 #include <asm/kmap_types.h>
26 
27 /* undef for production */
28 #define HIGHMEM_DEBUG 1
29 
30 /* declarations for highmem.c */
31 extern unsigned long highstart_pfn, highend_pfn;
32 
33 extern pte_t *pkmap_page_table;
34 
35 /*
36  * Right now we initialize only a single pte table. It can be extended
37  * easily, subsequent pte tables have to be allocated in one physical
38  * chunk of RAM.
39  */
40 #define LAST_PKMAP 1024
41 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
42 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
43 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
44 
45 extern void * kmap_high(struct page *page);
46 extern void kunmap_high(struct page *page);
47 
48 extern void *kmap(struct page *page);
49 extern void kunmap(struct page *page);
50 extern void *kmap_atomic(struct page *page);
51 extern void __kunmap_atomic(void *kvaddr);
52 extern void *kmap_atomic_pfn(unsigned long pfn);
53 extern struct page *kmap_atomic_to_page(void *ptr);
54 
55 #define flush_cache_kmaps() flush_cache_all()
56 
57 extern void kmap_init(void);
58 
59 #define kmap_prot PAGE_KERNEL
60 
61 #endif /* __KERNEL__ */
62 
63 #endif /* _ASM_HIGHMEM_H */