Intel MultiProcessor Specification, Offset, Length, Field, in bytes bits, in bits, Description

MultiProcessor Specification

Table 4-1. MP Floating Pointer Structure Fields (continued)

	Offset	Length
Field	(in bytes:bits)	(in bits)	Description
MP FEATURE	11	8	Bits 0-7:MP System Configuration Type.
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	7	Bits 0-6:Reserved for future MP definitions.
INFORMATION BYTE 2	12:7	1	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 3-5			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 7 of MP feature information byte 2, the IMCR present bit, is used by the operating system to determine whether PIC Mode or Virtual Wire Mode is implemented by the system.

The physical address pointer field contains the address of the beginning of the MP configuration table. If it is nonzero, the MP configuration table can be accessed at the physical address provided in the pointer structure. This field must be all zeros if the MP configuration table does not exist.

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