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Processor Configuration Registers
128
Datasheet, Volume 2
2.6.47
DCTL2—Device Control 2 Register
B/D/F/Type:
0/1/0–2/PCI
Address Offset:
C8–C9h
Reset Value:
0000h
Access:
RW-V, RW
Size:
16 bits
BIOS Optimal Default
0000h
Bit
Access
Reset 
Value
RST/
PWR
Description
15:12
RO
0h
Reserved (RSVD) 
11
RW-V
0b
Uncore
Latency Tolerance and BW Reporting Mechanism Enable 
(LTREN)
When set to 1b, this bit enables the Latency Tolerance & 
Bandwidth Requirement Reporting (LTBWR) mechanism.
This bit is required for all Functions that support the LTBWR 
Capability. For a Multi-Function device associated with an 
upstream port of a device that implements LTBWR, the bit in 
Function 0 is of type RW, and only Function 0 controls the 
component’s Link behavior. In all other Functions of that device, 
this bit is of type RsvdP.
Components that do not implement LTBWR are permitted to 
hardwire this bit to 0b.
Reset Value of this bit is 0b.
This bit is cleared when the port goes to DL_down state.
Hardware ignores the value of this bit.
10:6
RO
0h
Reserved (RSVD) 
5
RW
0b
Uncore
ARI Forward Enable (ARIFEN)
When set, the Downstream Port disables its traditional Device 
Number field being 0 enforcement when turning a Type 1 
Configuration Request into a Type 0 Configuration Request, 
permitting access to Extended Functions in an ARI Device 
immediately below the Port. 
Reset Value of this bit is 0b. It must be hardwired to 0b if the ARI 
Forwarding Supported bit is 0b.
4:0
RO
0h
Reserved (RSVD)