31

0x0

RW

VC1 Enable (VC1E)

This bit will be ignored by the hardware. The bit is R/W for specification compliance, but writing to it will result in no behavior change in the hardware (other than the bit value reflecting the written value).
0: Virtual Channel is disabled.
1: Virtual Channel is enabled.
See exceptions in note below.
Software must use the VC Negotiation Pending bit to check whether the VC negotiation is complete.
When VC Negotiation Pending bit is cleared, a 1 read from this VC Enable bit indicates that the VC is enabled (Flow Control Initialization is completed for the PCI Express port).
A 0 read from this bit indicates that the Virtual Channel is currently disabled.
Notes:
1. To enable a Virtual Channel, the VC Enable bits for that Virtual Channel must be set in both Components on a Link.
2. To disable a Virtual Channel, the VC Enable bits for that Virtual Channel must be cleared in both Components on a Link.
3. Software must ensure that no traffic is using a Virtual Channel at the time it is disabled. 4. Software must fully disable a Virtual Channel in both Components on a Link before re-enabling the Virtual Channel.

30:27

0h

RO

Reserved

26:24

0x1

RW

VC1 ID (VC1ID)

Assigns a VC ID to the VC resource. Assigned value must be non-zero. This field can not be modified when the VC is already enabled.

23:20

0h

RO

Reserved

19:17

0x0

RW

Port Arbitration Select (PAS)

This field configures the VC resource to provide a particular Port Arbitration service. The default value of 0h corresponds to bit position of the only asserted bit in the Port Arbitration Capability field.

16:8

0h

RO

Reserved

7:1

0x0

RW

TC/VC1 Map (TCVC1M)

Indicates the TCs (Traffic Classes) that are mapped to the VC resource. Bit locations within this field correspond to TC values. For example, when bit 7 is set in this field, TC7 is mapped to this VC resource. When more than one bit in this field is set, it indicates that multiple TCs are mapped to the VC resource. In order to remove one or more TCs from the TC/VC Map of an enabled VC, software must ensure that no new or outstanding transactions with the TC labels are targeted at the given Link.

0

0x0

RO

TC0/VC1 Map (TC0VC1M)

Traffic Class 0 is always routed to VC0.