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5dcd14ec PA |
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 | * | |
2e604c0f JB |
17 | * Note: efi_info is commonly left uninitialized, but that field has a |
18 | * private magic, so it is better to leave it unchanged. | |
5dcd14ec PA |
19 | */ |
20 | static void sanitize_boot_params(struct boot_params *boot_params) | |
21 | { | |
3c4aff6b PJ |
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 | */ | |
5dcd14ec | 36 | if (boot_params->sentinel) { |
3c4aff6b | 37 | /* fields in boot_params are left uninitialized, clear them */ |
d55e37bb | 38 | memset(&boot_params->ext_ramdisk_image, 0, |
2e604c0f | 39 | (char *)&boot_params->efi_info - |
d55e37bb | 40 | (char *)&boot_params->ext_ramdisk_image); |
5dcd14ec PA |
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 */ |