Intel MultiProcessor manual 4.1MP Floating Pointer Structure, 2.MP Floating Pointer Structure

MP Configuration Table

4.1MP Floating Pointer Structure

An MP-compliant system must implement the MP floating pointer structure, which is a variable length data structure in multiples of 16 bytes. Currently, only one 16-byte data structure is defined. It must span a minimum of 16 contiguous bytes, beginning on a 16-byte boundary, and it must be located within the physical address as specified in the previous section. To determine whether the system conforms to the MP specification, the operating system must search for the MP floating pointer structure in the order specified in the previous section. Figure 4-2 shows the format of this structure, and Table 4-1 explains each of the fields. See also Appendix E, for more information.

31		24 23	16 15	8	7		0
			MP FEATURE					0CH
			BYTES 2-5
		MP FEATURE	CHECKSUM	SPEC_REV		LENGTH		08H
		BYTE 1
			PHYSICAL ADDRESS POINTER					04H
			SIGNATURE					00H
		_ (5Fh)	P (50h)	M (4Dh)		_ (5Fh)
31		24 23	16 15	8	7		0
		Figure 4-2. MP Floating Pointer Structure
	Table 4-1. MP Floating Pointer Structure Fields
		Offset	Length
	Field	(in bytes:bits) (in bits)		Description
	SIGNATURE	0	32	The ASCII string represented by “_MP_” which
				serves as a search key for locating the pointer
				structure.
	PHYSICAL ADDRESS	4	32	The address of the beginning of the MP
	POINTER			configuration table. All zeros if the MP
				configuration table does not exist.
	LENGTH	8	8	The length of the floating pointer structure table
				in paragraph (16-byte) units. The structure is
				16 bytes or 1 paragraph long; so this field
				contains 01h.
	SPEC_REV	9	8	The version number of the MP specification
				supported. A value of 01h indicates Version 1.1.
				A value of 04h indicates Version 1.4.
	CHECKSUM	10	8	A checksum of the complete pointer structure.
				All bytes specified by the length field, including

CHECKSUM and reserved bytes, must add up to zero.

Version 1.4 4-3