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ACPICA: Remove use of unreliable FADT revision field

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The revision number in the FADT has been found to be completely
unreliable and cannot be trusted. Only the table length can be
used to infer the actual version.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Bob Moore 2011-02-14 15:50:42 +08:00 committed by Len Brown
parent 6dfad33964
commit 64b3db22c0
2 changed files with 20 additions and 1 deletions
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5
drivers/acpi/acpica/tbfadt.c
View file

@ -384,8 +384,11 @@ static void acpi_tb_convert_fadt(void)
*
* The ACPI 1.0 reserved fields that will be zeroed are the bytes located at
* offset 45, 55, 95, and the word located at offset 109, 110.
*
* Note: The FADT revision value is unreliable. Only the length can be
* trusted.
*/
if (acpi_gbl_FADT.header.revision < FADT2_REVISION_ID) {
if (acpi_gbl_FADT.header.length <= ACPI_FADT_V2_SIZE) {
acpi_gbl_FADT.preferred_profile = 0;
acpi_gbl_FADT.pstate_control = 0;
acpi_gbl_FADT.cst_control = 0;

16
include/acpi/actbl.h
View file

@ -343,4 +343,20 @@ struct acpi_table_desc {
#include <acpi/actbl1.h>
#include <acpi/actbl2.h>
/*
* Sizes of the various flavors of FADT. We need to look closely
* at the FADT length because the version number essentially tells
* us nothing because of many BIOS bugs where the version does not
* match the expected length. In other words, the length of the
* FADT is the bottom line as to what the version really is.
*
* For reference, the values below are as follows:
* FADT V1 size: 0x74
* FADT V2 size: 0x84
* FADT V3+ size: 0xF4
*/
#define ACPI_FADT_V1_SIZE (u32) (ACPI_FADT_OFFSET (flags) + 4)
#define ACPI_FADT_V2_SIZE (u32) (ACPI_FADT_OFFSET (reserved4[0]) + 3)
#define ACPI_FADT_V3_SIZE (u32) (sizeof (struct acpi_table_fadt))
#endif /* __ACTBL_H__ */