Host-PCI Express* Graphics Bridge Registers (D1:F0)
R
Intel
®
82925X/82925XE MCH Datasheet
109
8
Host-PCI Express* Graphics
Bridge Registers (D1:F0)
Device 1contains the controls associated with the PCI Express x16 root port that is the intended to
attach as the point for external graphics. It is typically referred to as PCI Express* x16 Graphics
Interface port. In addition, it also functions as the virtual PCI-to-PCI bridge.
Warning:
When reading the PCI Express "conceptual" registers such as this, you may not get a valid value
unless the register value is stable.
The
PCI Express* Specification
defines two types of reserved bits: Reserved and Preserved:
•
Reserved for future R/W implementations; software must preserve value read for writes to
bits.
•
Reserved and Zero: Reserved for future R/WC/S implementations; software must use 0 for
writes to bits.
Unless explicitly documented as Reserved and Zero, all bits marked as reserved are part of the
Reserved and Preserved type that have historically been the typical definition for Reserved.
It is important to note that most (if not all) control bits in this device cannot be modified unless
the link is down. Software is required to first Disable the link, then program the registers, and
then re-enable the link (which will cause a full-retrain with the new settings).
Table 8-1. Host-PCI Express* Graphics Bridge Register Address Map (D1:F0)
Address
Offset
Register
Symbol
Register Name
Default
Value
Access
00–01h VID1
Vendor
Identification
8086h RO
02–03h DID1
Device
Identification
2581h RO
04–05h
PCICMD1
PCI Command
0000h
RO, R/W
06–07h
PCISTS1
PCI Status
0000h
RO, R/W
08h
RID1
Revision Identification
See Register
Description
RO
09–0Bh CC1
Class
Code
060400h
RO
0Ch
CL1
Cache Line Size
00h
R/W
0Dh —
Reserved
— —
0Eh HDR1
Header
Type
01h RO
0F–17h —
Reserved
— —
18h
PBUSN1
Primary Bus Number
00h
RO
19h
SBUSN1
Secondary Bus Number
00h
RO
1Ah
SUBUSN1
Subordinate Bus Number
00h
R/W
Содержание 82925X
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