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 */ 20 static 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