Host-PCI Express* Graphics Bridge Registers (D1:F0)
R
Intel
®
82925X/82925XE MCH Datasheet
119
8.1.12
IOBASE1—I/O Base Address (D1:F0)
PCI Device:
1
Address Offset:
1Ch
Default Value:
F0h
Access: RO
Size: 8
bits
This register controls the processor-to-PCI Express Graphics I/O access routing based on the
following formula:
IO_BASE
≤
address
≤
IO_LIMIT
Only the upper 4 bits are programmable. For the purpose of address decode, address bits A[11:0]
are treated as 0. Thus, the bottom of the defined I/O address range will be aligned to a 4-KB
boundary.
Bit Access
&
Default
Description
7:4 R/W
Fh
I/O Address Base (IOBASE):
This field corresponds to A[15:12] of the I/O
addresses passed by bridge 1 to PCI Express*-G. BIOS must not set this register
to 00h; otherwise, 0CF8h/0CFCh accesses will be forwarded to the PCI Express
hierarchy associated with this device.
3:0
Reserved
8.1.13
IOLIMIT1—I/O Limit Address (D1:F0)
PCI Device:
1
Address Offset:
1Dh
Default Value:
00h
Access: R/W
Size: 8
bits
This register controls the processor-to-PCI Express Graphics I/O access routing based on the
following formula:
IO_BASE
≤
address
≤
IO_LIMIT
Only the upper 4 bits are programmable. For the purposes of address decode, address bits A[11:0]
are assumed to be FFFh. Thus, the top of the defined I/O address range will be at the top of a
4-KB aligned address block.
Bit Access
&
Default
Description
7:4 R/W
0h
I/O Address Limit (IOLIMIT):
This field corresponds to A[15:12] of the I/O
address limit of device 1. Devices between this upper limit and IOBASE1 will be
passed to the PCI Express* hierarchy associated with this device.
3:0
Reserved
Summary of Contents for 82925X
Page 78: ...Host Bridge DRAM Controller Registers D0 F0 R 78 Intel 82925X 82925XE MCH Datasheet...
Page 98: ...EPBAR Registers Egress Port Register Summary R 98 Intel 82925X 82925XE MCH Datasheet...
Page 108: ...DMIBAR Registers Direct Media Interface DMI RCRB R 108 Intel 82925X 82925XE MCH Datasheet...
Page 156: ...Host PCI Express Graphics Bridge Registers D1 F0 R 156 Intel 82925X 82925XE MCH Datasheet...
Page 172: ...System Address Map R 172 Intel 82925X 82925XE MCH Datasheet...
Page 192: ...Electrical Characteristics R 192 Intel 82925X 82925XE MCH Datasheet...