82801BA Datasheet, PDF (306/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

LPC Interface Bridge Registers (D31:F0)
9.5.7
9.5.8
a
9.5.9
a
VER—Version Register
Index Offset:
Default Value:
01h
00170002h
Attribute:
Size:
RO
32 bits
Each I/O APIC contains a hardwired Version Register that identifies different implementation of
APIC and their versions. The maximum redirection entry information also is in this register, to let
software know how many interrupt are supported by this APIC.
Bit
Description
31:24
23:16
15
14 :8
7:0
Reserved.
Maximum Redirection Entries—RO. This is the entry number (0 being the lowest entry) of the
highest entry in the redirection table. It is equal to the number of interrupt input pins minus one and
is in the range 0 through 239. In the ICH2 this field is hardwired to 17h to indicate 24 interrupts.
PRQ—RO. This bit is set to 1 to indicate that this version of the I/O APIC implements the IRQ
Assertion register and allows PCI devices to write to it to cause interrupts.
Reserved.
Version—RO. This is a version number that identifies the implementation version.
ARBID—Arbitration ID Register
Index Offset:
Default Value:
02h
00000000h
Attribute:
Size:
RO
32 bits
This register contains the bus arbitration priority for the APIC. This register is loaded whenever the
APIC ID register is loaded. A rotating priority scheme is used for APIC bus arbitration. The winner
of the arbitration becomes the lowest priority agent and assumes an arbitration ID of 0.
Bit
31:28
27:24
23:0
Description
Reserved.
I/O APIC Identification—RO. This 4 bit field contains the I/O APIC Arbitration ID.
Reserved.
BOOT_CONFIG—Boot Configuration Register
Index Offset:
Default Value:
03h
00000000h
Attribute:
Size:
R/W
32 bits
This register is used to control the interrupt delivery mechanism for the APIC.
Bit
31:1
0
Description
Reserved.
Delivery Type (DT)—R/W.
0 = Interrupt delivery mechanism is via the APIC serial bus (default).
1 = Interrupt delivery mechanism is a front-side bus message.
9-44
82801BA ICH2 and 82801BAM ICH2-M Datasheet