MultiProcessor Specification
Table
| 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. |
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|
|
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 |
|
|
| 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. |
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|
| A value of 04h indicates Version 1.4. |
|
|
|
|
CHECKSUM | 10 | 8 | A checksum of the complete pointer structure. |
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| All bytes specified by the length field, including |
|
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| CHECKSUM and reserved bytes, must add up to |
|
|
| zero. |
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|
|
MP FEATURE | 11 | 8 | Bits |
INFORMATION BYTE 1 |
|
| 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 | 12:0 | 6 |
INFORMATION BYTE 2 | 12:6 | 1 |
12:71
Bits
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 | 13 | 24 | Reserved for future MP definitions. Must be |
INFORMATION BYTES |
|
| zero. |
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|
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
indicate that all processors derive their clock from a common source. Bit 7 of MP feature
Version 1.4 |
