1 files changed, 16 insertions, 0 deletions

diff --git a/include/acpi/actbl.h b/include/acpi/actbl.h
index 7e42bfee0e2..d41c9488521 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__ */