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kernel/linux-rt-4.4.41/arch/x86/include/asm/bootparam_utils.h 1.95 KB
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  #ifndef _ASM_X86_BOOTPARAM_UTILS_H
  #define _ASM_X86_BOOTPARAM_UTILS_H
  
  #include <asm/bootparam.h>
  
  /*
   * This file is included from multiple environments.  Do not
   * add completing #includes to make it standalone.
   */
  
  /*
   * Deal with bootloaders which fail to initialize unknown fields in
   * boot_params to zero.  The list fields in this list are taken from
   * analysis of kexec-tools; if other broken bootloaders initialize a
   * different set of fields we will need to figure out how to disambiguate.
   *
   * Note: efi_info is commonly left uninitialized, but that field has a
   * private magic, so it is better to leave it unchanged.
   */
  static void sanitize_boot_params(struct boot_params *boot_params)
  {
  	/* 
  	 * IMPORTANT NOTE TO BOOTLOADER AUTHORS: do not simply clear
  	 * this field.  The purpose of this field is to guarantee
  	 * compliance with the x86 boot spec located in
  	 * Documentation/x86/boot.txt .  That spec says that the
  	 * *whole* structure should be cleared, after which only the
  	 * portion defined by struct setup_header (boot_params->hdr)
  	 * should be copied in.
  	 *
  	 * If you're having an issue because the sentinel is set, you
  	 * need to change the whole structure to be cleared, not this
  	 * (or any other) individual field, or you will soon have
  	 * problems again.
  	 */
  	if (boot_params->sentinel) {
  		/* fields in boot_params are left uninitialized, clear them */
  		memset(&boot_params->ext_ramdisk_image, 0,
  		       (char *)&boot_params->efi_info -
  			(char *)&boot_params->ext_ramdisk_image);
  		memset(&boot_params->kbd_status, 0,
  		       (char *)&boot_params->hdr -
  		       (char *)&boot_params->kbd_status);
  		memset(&boot_params->_pad7[0], 0,
  		       (char *)&boot_params->edd_mbr_sig_buffer[0] -
  			(char *)&boot_params->_pad7[0]);
  		memset(&boot_params->_pad8[0], 0,
  		       (char *)&boot_params->eddbuf[0] -
  			(char *)&boot_params->_pad8[0]);
  		memset(&boot_params->_pad9[0], 0, sizeof(boot_params->_pad9));
  	}
  }
  
  #endif /* _ASM_X86_BOOTPARAM_UTILS_H */