Datasheet

PCI Express Non-Transparent Bridge
Intel
®
Xeon
®
Processor C5500/C3500 Series
Datasheet, Volume 1 February 2010
160 Order Number: 323103-001
3.8 Outbound Transactions
This section describes the NTB behavior towards outbound transactions to an external
agent on the PCIE link. Throughout the rest of the chapter, outbound refers to the
direction from CPU towards I/O.
3.8.1 Memory, I/O and Configuration Transactions
The IIO will generate outbound memory transactions to NTB MMIO space and to
memory on an external agent connected to the secondary side of the NTB across the
PCI Express link.
The IIO will never generate I/O and configuration cycles that are sent outbound on the
PCI Express link. The IIO will generate configuration cycles to the primary side of the
NTB. All transaction behavior are listed in Table 83.
Table 83. Outgoing PCI Express Memory, I/O and Configuration Request/Completion
Cycles
PCI Express
Transaction
Address Space
or Message
Reason for Issue
Outbound Write
Requests
Memory
Accepted by the NTB if targeting MMIO space claimed by the NTB or after address detection
and translation sent from the primary side to the secondary side of the NTB and on the link
partner connected to the secondary side of the NTB.
I/O CPU will never generate an IO requests to the NTB so this will never occur.
Configuration
Accepted by the NTB if targeted to the primary side of the NTB. (Positive decoded)
Configuration transactions will never be sent outbound on the wire as the NTB is an
endpoint so this will never occur.
Outbound
Completions for
Inbound Write
Requests
I/O
The NTB does not claim any IO space resources and as such should never be the recipient
of an inbound IO request. If this occurs it will be returned to the requester with completion
status of UR.
Type 0
Configuration
Response from inbound Type 0 configuration requests targeted to the secondary side
configuration space of the NTB. All other configuration cycles are unsupported and are
returned with completion status of UR.
Note: This will only be seen in case of NTB/RP. In NTB/NTB case configuration transaction
will not be seen on the wire.
Type 1
Configuration
Type 1 configurations are not supported and are returned with completion status of UR
Outbound Read
Requests
Memory
Accepted by the NTB if targeting MMIO space claimed by the NTB or after address detection
and translation sent from the primary side to the secondary side of the NTB and on the link
partner connected to the secondary side of the NTB.
I/O CPU will never generate an IO requests to the NTB so this will never occur.
Configuration
Accepted by the NTB if targeted to the primary side of the NTB. (Positive decoded)
Configuration transactions will never be sent outbound on the wire as the NTB is an
endpoint so this will never occur.
Outbound
Completions for
Inbound Read
Requests
Memory
Response for an inbound read targeting MMIO space claimed by the NTB, or after address
detection and translation sent from the secondary side to the primary side of the NTB
targeting main memory or a peer I/O device.
I/O
The NTB does not claim any IO space resources and as such should never be the recipient
of an inbound IO request. If this occurs it will be returned to the requester with completion
status of UR.
Type 0
Configuration
Response from inbound Type 0 configuration requests targeted to the secondary side
configuration space of the NTB. All other configuration cycles are unsupported and are
returned with completion status of UR.
Note: This will only be seen in case of NTB/RP. In NTB/NTB case configuration transaction
will not be seen on the wire.
Type 1
Configuration
Type 1 configurations are not supported and are returned with completion status of UR