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kernel/linux-rt-4.4.41/arch/x86/include/asm/bios_ebda.h 1.33 KB
5113f6f70   김현기   kernel add
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  #ifndef _ASM_X86_BIOS_EBDA_H
  #define _ASM_X86_BIOS_EBDA_H
  
  #include <asm/io.h>
  
  /*
   * Returns physical address of EBDA.  Returns 0 if there is no EBDA.
   */
  static inline unsigned int get_bios_ebda(void)
  {
  	/*
  	 * There is a real-mode segmented pointer pointing to the
  	 * 4K EBDA area at 0x40E.
  	 */
  	unsigned int address = *(unsigned short *)phys_to_virt(0x40E);
  	address <<= 4;
  	return address;	/* 0 means none */
  }
  
  /*
   * Return the sanitized length of the EBDA in bytes, if it exists.
   */
  static inline unsigned int get_bios_ebda_length(void)
  {
  	unsigned int address;
  	unsigned int length;
  
  	address = get_bios_ebda();
  	if (!address)
  		return 0;
  
  	/* EBDA length is byte 0 of the EBDA (stored in KiB) */
  	length = *(unsigned char *)phys_to_virt(address);
  	length <<= 10;
  
  	/* Trim the length if it extends beyond 640KiB */
  	length = min_t(unsigned int, (640 * 1024) - address, length);
  	return length;
  }
  
  void reserve_ebda_region(void);
  
  #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
  /*
   * This is obviously not a great place for this, but we want to be
   * able to scatter it around anywhere in the kernel.
   */
  void check_for_bios_corruption(void);
  void start_periodic_check_for_corruption(void);
  #else
  static inline void check_for_bios_corruption(void)
  {
  }
  
  static inline void start_periodic_check_for_corruption(void)
  {
  }
  #endif
  
  #endif /* _ASM_X86_BIOS_EBDA_H */