Intel MultiProcessor Base MP Configuration Table Entries, MP Configuration Table Header Fields

MultiProcessor Specification

Table 4-2. MP Configuration Table Header Fields

	Offset	Length
Field	(in bytes)	(in bits)	Description
SIGNATURE	0	32	The ASCII string representation of “PCMP,” which
			confirms the presence of the table.
BASE TABLE LENGTH	4	16	The length of the base configuration table in bytes,
			including the header, starting from offset 0. This field
			aids in calculation of the checksum.
SPEC_REV	6	8	The version number of the MP specification. A value
			of 01h indicates Version 1.1. A value of 04h indicates
			Version 1.4.
CHECKSUM	7	8	A checksum of the entire base configuration table. All
			bytes, including CHECKSUM and reserved bytes,
			must add up to zero.
OEM ID	8	64	A string that identifies the manufacturer of the system
			hardware.
PRODUCT ID	16	96	A string that identifies the product family.
OEM TABLE POINTER	28	32	A physical-address pointer to an OEM-defined
			configuration table. This table is optional. If not
			present, this field is zero.
OEM TABLE SIZE	32	16	The size of the base OEM table in bytes. If the table
			is not present, this field is zero.
ENTRY COUNT	34	16	The number of entries in the variable portion of the
			base table. This field helps the software identify the
			end of the table when stepping through the entries.
ADDRESS OF LOCAL APIC	36	32	The base address by which each processor accesses
			its local APIC.
EXTENDED TABLE	40	16	Length in bytes of the extended entries that are
LENGTH			located in memory at the end of the base
			configuration table. A zero value in this field indicates
			that no extended entries are present.
EXTENDED TABLE	42	8	Checksum for the set of extended table entries,
CHECKSUM			including only extended entries starting from the end
			of the base configuration table. When no extended
			table is present, this field is zero.

4.3Base MP Configuration Table Entries

A variable number of variable length entries follow the header of the MP configuration table. The first byte of each entry identifies the entry type. Each entry type has a known, fixed length. The total length of the MP configuration table depends upon the configuration of the system. Software must step through each entry in the base table until it reaches ENTRY COUNT. The entries are sorted on ENTRY TYPE in ascending order. Table 4-3 gives the meaning of each value of

ENTRY TYPE.

4-6 Version 1.4