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MultiProcessor Specification
E-2 Version 1.4
Table 4-1. MP Floating Pointer Structure Fields
Field
Offset
(in bytes:bits)
Length
(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
POINTER
4 32 The address of the beginning of the MP
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.
MP FEATURE
INFORMATION BYTE 1
11 8
Bits 0-7:
MP System Configuration Type.
When these bits are all zeros, the MP
configuration table is present. When nonzero,
the value indicates which default configuration
(as defined in Chapter 5) is implemented by the
system.
MP FEATURE
INFORMATION BYTE 2
12:0
12:6
12:7
6
1
1
Bits 0-5
:
Reserved for future MP definitions.
Bit 6:
Multiple Clock Sources. When set, this bit
indicates that the processors derive clock signals
from different sources. Otherwise when not set
this bit indicates that all processors share a
single clock source.
Bit 7:
IMCRP. When the IMCR presence bit is
set, the IMCR is present and PIC Mode is
implemented; otherwise, Virtual Wire Mode is
implemented.
MP FEATURE
INFORMATION BYTES 3-5
13 24 Reserved for future MP definitions. Must be
zero.
The MP feature information byte 1 specifies the MP system default configuration type. If nonzero,
the system configuration conforms to one of the default configurations. The default configurations,
specified in Chapter 5, may only be used to describe systems that always have two processors
installed.
Bit 6 of MP feature information byte 2, the Multiple Clock Source bit, is used by the operating
system to determine how processors derive clock sources. If the system design does not provide
for a single clock source shared by all processors then this bit is set. Otherwise this bit is zero to
in
dicate that all processors derive their clock
from
a common source.
Bit 7 of MP feature