LXR linux/arch/x86/include/asm/bios

   1#ifndef _ASM_X86_BIOS_EBDA_H
   2#define _ASM_X86_BIOS_EBDA_H
   3
   4#include <asm/io.h>
   5
   6/*
   7 * Returns physical address of EBDA.  Returns 0 if there is no EBDA.
   8 */
   9static inline unsigned int get_bios_ebda(void)
  10{
  11        /*
  12         * There is a real-mode segmented pointer pointing to the
  13         * 4K EBDA area at 0x40E.
  14         */
  15        unsigned int address = *(unsigned short *)phys_to_virt(0x40E);
  16        address <<= 4;
  17        return address; /* 0 means none */
  18}
  19
  20/*
  21 * Return the sanitized length of the EBDA in bytes, if it exists.
  22 */
  23static inline unsigned int get_bios_ebda_length(void)
  24{
  25        unsigned int address;
  26        unsigned int length;
  27
  28        address = get_bios_ebda();
  29        if (!address)
  30                return 0;
  31
  32        /* EBDA length is byte 0 of the EBDA (stored in KiB) */
  33        length = *(unsigned char *)phys_to_virt(address);
  34        length <<= 10;
  35
  36        /* Trim the length if it extends beyond 640KiB */
  37        length = min_t(unsigned int, (640 * 1024) - address, length);
  38        return length;
  39}
  40
  41void reserve_ebda_region(void);
  42
  43#ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
  44/*
  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.
  47 */
  48void check_for_bios_corruption(void);
  49void start_periodic_check_for_corruption(void);
  50#else
  51static inline void check_for_bios_corruption(void)
  52{
  53}
  54
  55static inline void start_periodic_check_for_corruption(void)
  56{
  57}
  58#endif
  59
  60#endif /* _ASM_X86_BIOS_EBDA_H */
  61