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[cris-mirror.git] / arch / x86 / include / asm / bios_ebda.h
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1 #ifndef _ASM_X86_BIOS_EBDA_H
2 #define _ASM_X86_BIOS_EBDA_H
4 #include <asm/io.h>
6 /*
7 * Returns physical address of EBDA. Returns 0 if there is no EBDA.
8 */
9 static inline unsigned int get_bios_ebda(void)
12 * There is a real-mode segmented pointer pointing to the
13 * 4K EBDA area at 0x40E.
15 unsigned int address = *(unsigned short *)phys_to_virt(0x40E);
16 address <<= 4;
17 return address; /* 0 means none */
21 * Return the sanitized length of the EBDA in bytes, if it exists.
23 static inline unsigned int get_bios_ebda_length(void)
25 unsigned int address;
26 unsigned int length;
28 address = get_bios_ebda();
29 if (!address)
30 return 0;
32 /* EBDA length is byte 0 of the EBDA (stored in KiB) */
33 length = *(unsigned char *)phys_to_virt(address);
34 length <<= 10;
36 /* Trim the length if it extends beyond 640KiB */
37 length = min_t(unsigned int, (640 * 1024) - address, length);
38 return length;
41 void reserve_ebda_region(void);
43 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
45 * This is obviously not a great place for this, but we want to be
46 * able to scatter it around anywhere in the kernel.
48 void check_for_bios_corruption(void);
49 void start_periodic_check_for_corruption(void);
50 #else
51 static inline void check_for_bios_corruption(void)
55 static inline void start_periodic_check_for_corruption(void)
58 #endif
60 #endif /* _ASM_X86_BIOS_EBDA_H */