+#define ACPI_FADT_OFFSET(f) (UINT16) ACPI_OFFSET (ACPI_TABLE_FADT, f)
+
+/*
+ * 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: 0x074
+ * FADT V2 size: 0x084
+ * FADT V3 size: 0x0F4
+ * FADT V4 size: 0x0F4
+ * FADT V5 size: 0x10C
+ */
+#define ACPI_FADT_V1_SIZE (UINT32) (ACPI_FADT_OFFSET (Flags) + 4)
+#define ACPI_FADT_V2_SIZE (UINT32) (ACPI_FADT_OFFSET (Reserved4[0]) + 3)
+#define ACPI_FADT_V3_SIZE (UINT32) (ACPI_FADT_OFFSET (SleepControl))
+#define ACPI_FADT_V5_SIZE (UINT32) (sizeof (ACPI_TABLE_FADT))