Mp Floating Pointer Structure - Intel MultiProcessor Specification

4.1

MP 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.
Table 4-1. MP Floating Pointer Structure Fields
Field
SIGNATURE
PHYSICAL ADDRESS
POINTER
LENGTH
SPEC_REV
CHECKSUM
Version 1.4
31 24 23
MP FEATURE
BYTES 2-5
MP FEATURE
CHECKSUM
BYTE 1
PHYSICAL ADDRESS POINTER
SIGNATURE
_ (5Fh) P (50h)
31 24 23
Figure 4-2. MP Floating Pointer Structure
Offset Length
(in bytes:bits) (in bits)
0 32
4 32
8 8
9 8
10 8
See also Appendix E, for more information.
16 15 8 7
SPEC_REV LENGTH
M (4Dh) _ (5Fh)
16 15 8 7
Description
The ASCII string represented by "_MP_" which
serves as a search key for locating the pointer
structure.
The address of the beginning of the MP
configuration table. All zeros if the MP
configuration table does not exist.
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.
The version number of the MP specification
supported. A value of
A value of 04h indicates Version
A checksum of the complete pointer structure.
All bytes specified by the length field, including
CHECKSUM and reserved bytes, must add up to
zero.
MP Configuration Table
0
0CH
08 H
04H
00H
0
01h indicates Version 1.1.
1.4.
4-3