Datasheet
Interfaces
Intel
®
Xeon
®
Processor C5500/C3500 Series
Datasheet, Volume 1 February 2010
116 Order Number: 323103-001
2.5.8 Inbound Coherent
The IIO only sends a subset of the coherent transactions supported in Intel
®
QPI. This
section describes only the transactions that are considered coherent. The
determination of Coherent versus Non-Coherent is made by the address decode. If a
transaction is determined coherent by address decode, it may still be changed to non-
coherent as a result of its PCI Express attributes.
The IIO supports only source broadcast snooping, with the Invalidating Write Back flow.
In source broadcast mode, the IIO sends a snoop to all peer caching (
it does not send a
snoop to peer IIO caching agent)
participants when initiating a new coherent request.
The snoop is sent to non-Home node (CPU) only in DP systems. Which peer caching
agents are snooped is determined by the snoop participant list. The snoop participant
list comprises a list of NodeIDs which must receive snoops for a given coherent
request. The IIO’s NodeID is masked from the snoop participant list to prevent a snoop
being sent back to the IIO”, and following “The snoop participant list is programmed in
QPIPSB.
2.5.9 Inbound Non-Coherent
Support is provided for a non-coherent broadcast list to deal with non-coherent
requests that are broadcast to multiple agents. Transaction types that use this flow:
• Broadcast Interrupts
•Power management requests
• Lock flow
There are three non-coherent broadcast lists
• The primary list is the “non-coherent broadcast list” which is used for power
management, and Broadcast Interrupts. This list will be programmed to include all
processors.
• The Lock Arbiter list of IIOs
• The Lock Arbiter list of processors
The broadcast lists are implemented with an 8-bit vector corresponding to NodeIDs
0-7. Each bit in this vector corresponds to a destination NodeID receiving the
broadcast.
The Transaction ID (TID) allocation scheme used by the IIO results in a unique TID for
each non-coherent request that is broadcast (i.e. for each broadcast interrupt, each
request will use a unique TID). See Section 2.5.13 for additional details on the TID
allocation.
Broadcast to the IIO’s local NodeID will only be spawned internally and do not appear
on the Intel
®
QPI bus.
2.5.9.1 Peer-to-Peer Tunneling
The IIO supports peer-to-peer tunneling of MRd, MWr, CplD, CpI, MsgD and Msg PCI
Express messages. Peer-to-peer traffic between PCIe and DMI is not supported.
2.5.10 Profile Support
The IIO will support UP and DP profiles set through configuration registers. Table 66
defines which register settings are required for each profile. There is not a single
register setting for a given profile, but rather a set of registers that must be
programmed to match Table 66.