This should help avoid making the incorrect change in non-compliant
bootloaders.
Signed-off-by: Peter Jones <pjo...@redhat.com>
---
Documentation/x86/boot.txt | 5 +++--
arch/x86/include/asm/bootparam_utils.h | 7 +++++++
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 3840b6f..72702db 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -1110,7 +1110,8 @@ firmware, 'table' is the EFI system table - these are the
first two
arguments of the "handoff state" as described in section 2.3 of the
UEFI specification. 'bp' is the boot loader-allocated boot params.
-The boot loader *must* fill out the following fields in bp,
+The boot loader *must* zero the entirity of bp, and then fill out the
+following fields:
o hdr.code32_start
o hdr.cmd_line_ptr
@@ -1118,4 +1119,4 @@ The boot loader *must* fill out the following fields in
bp,
o hdr.ramdisk_image (if applicable)
o hdr.ramdisk_size (if applicable)
-All other fields should be zero.
+All other fields should remain zero.
diff --git a/arch/x86/include/asm/bootparam_utils.h
b/arch/x86/include/asm/bootparam_utils.h
index 5b5e9cb..b4e8aa8 100644
--- a/arch/x86/include/asm/bootparam_utils.h
+++ b/arch/x86/include/asm/bootparam_utils.h
@@ -17,6 +17,13 @@
*/
static void sanitize_boot_params(struct boot_params *boot_params)
{
+ /* Note: 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. 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) indidivual field.
+ */
if (boot_params->sentinel) {
/*fields in boot_params are not valid, clear them */
memset(&boot_params->olpc_ofw_header, 0,
--
1.8.1.4
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