diff options
| -rw-r--r-- | drivers/acpi/acpica/tbfadt.c | 5 | ||||
| -rw-r--r-- | include/acpi/actbl.h | 16 |
2 files changed, 20 insertions, 1 deletions
diff --git a/drivers/acpi/acpica/tbfadt.c b/drivers/acpi/acpica/tbfadt.c index 428d44e2d162..6f5588e62c0a 100644 --- a/drivers/acpi/acpica/tbfadt.c +++ b/drivers/acpi/acpica/tbfadt.c @@ -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; diff --git a/include/acpi/actbl.h b/include/acpi/actbl.h index 7e42bfee0e29..d41c94885211 100644 --- a/include/acpi/actbl.h +++ b/include/acpi/actbl.h @@ -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__ */ |