LXR linux/arch/x86/include/asm/bootparam

   1#ifndef _ASM_X86_BOOTPARAM_UTILS_H
   2#define _ASM_X86_BOOTPARAM_UTILS_H
   3
   4#include <asm/bootparam.h>
   5
   6/*
   7 * This file is included from multiple environments.  Do not
   8 * add completing #includes to make it standalone.
   9 */
  10
  11/*
  12 * Deal with bootloaders which fail to initialize unknown fields in
  13 * boot_params to zero.  The list fields in this list are taken from
  14 * analysis of kexec-tools; if other broken bootloaders initialize a
  15 * different set of fields we will need to figure out how to disambiguate.
  16 *
  17 * Note: efi_info is commonly left uninitialized, but that field has a
  18 * private magic, so it is better to leave it unchanged.
  19 */
  20static void sanitize_boot_params(struct boot_params *boot_params)
  21{
  22        /* 
  23         * IMPORTANT NOTE TO BOOTLOADER AUTHORS: do not simply clear
  24         * this field.  The purpose of this field is to guarantee
  25         * compliance with the x86 boot spec located in
  26         * Documentation/x86/boot.txt .  That spec says that the
  27         * *whole* structure should be cleared, after which only the
  28         * portion defined by struct setup_header (boot_params->hdr)
  29         * should be copied in.
  30         *
  31         * If you're having an issue because the sentinel is set, you
  32         * need to change the whole structure to be cleared, not this
  33         * (or any other) individual field, or you will soon have
  34         * problems again.
  35         */
  36        if (boot_params->sentinel) {
  37                /* fields in boot_params are left uninitialized, clear them */
  38                memset(&boot_params->ext_ramdisk_image, 0,
  39                       (char *)&boot_params->efi_info -
  40                        (char *)&boot_params->ext_ramdisk_image);
  41                memset(&boot_params->kbd_status, 0,
  42                       (char *)&boot_params->hdr -
  43                       (char *)&boot_params->kbd_status);
  44                memset(&boot_params->_pad7[0], 0,
  45                       (char *)&boot_params->edd_mbr_sig_buffer[0] -
  46                        (char *)&boot_params->_pad7[0]);
  47                memset(&boot_params->_pad8[0], 0,
  48                       (char *)&boot_params->eddbuf[0] -
  49                        (char *)&boot_params->_pad8[0]);
  50                memset(&boot_params->_pad9[0], 0, sizeof(boot_params->_pad9));
  51        }
  52}
  53
  54#endif /* _ASM_X86_BOOTPARAM_UTILS_H */
  55