Datasheet

Processor Configuration Registers
166 Datasheet, Volume 2
2.12.9 DMIVC1RCTL1—DMI VC1 Resource Control Register
This register controls the resources associated with PCI Express Virtual Channel 1.
B/D/F/Type: 0/0/0/DMIBAR
Address Offset: 20–23h
Reset Value: 0100_0000h
Access: RO, RW
Bit Attr
Reset
Value
Description
31 RW 0b
Virtual Channel Enable (VCE)
0 = Virtual Channel is disabled.
1 = Virtual Channel is enabled. See exceptions 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.
BIOS Requirement:
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 RO 0h Reserved
26:24 RW 001b
Virtual Channel ID (VCID)
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 RO 0h Reserved
19:17 RW 000b
Port Arbitration Select (PAS)
This field configures the VC resource to provide a particular Port Arbitration
service. Valid value for this field is a number corresponding to one of the
asserted bits in the Port Arbitration Capability field of the VC resource.
16:8 RO 000h Reserved
7:1 RW 00h
Traffic Class / Virtual Channel Map (TCVCM)
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.
BIOS Requirement: Program this field, including bit 0, with the value
00100010b (22h), which maps TC1 and TC5 to VC1.
0RO 0b
Traffic Class 0 / Virtual Channel 1 Map (TC0VC1M)
Traffic Class 0 is always routed to VC0.