Intel MultiProcessor manual Bus Entries, Bus Id, BUS Type, String

MultiProcessor Specification

4.3.2 Bus Entries

Bus entries identify the kinds of buses in the system. Because there may be more than one bus in a system, each bus is assigned a unique bus ID number by the BIOS. The bus ID number is used by the operating system to associate interrupt lines with specific buses. Figure 4-5 shows the format of a bus entry, and Table 4-7 explains the fields of each entry.

31	24	23	16		15	8	7	0
			BUS TYPE STRING
					BUS ID			ENTRY TYPE
								1
31	24	23	16		15	8	7	0

04H

00H

Figure 4-5. Bus Entry

Table 4-7. Bus Entry Fields

	Offset	Length
Field	(in bytes)	(in bits)	Description
ENTRY TYPE	0	8	Entry type 1 identifies a bus entry.
BUS ID	1	8	An integer that identifies the bus entry. The BIOS assigns
			identifiers sequentially, starting at zero.
BUS TYPE	2	48	A string that identifies the type of bus. Refer to Table 4-8 for
STRING			values. These are 6-character ASCII (blank-filled) strings
			used by the MP specification.

4-10 Version 1.4