IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 50 / 744

IDT PES32NT24xG2 Device Overview
PES32NT24xG2 User Manual 1 - 14 January 30, 2013
Notes
either partition and write data to a memory address in the other partition. To read or write data from the
partition across the NTB (i.e., partition 1 in this example), the DMA need only be programmed to issue the
read/write transactions to addresses that map to one of the memory windows of the NT function in partition
0.
– Memory read or write request TLPs issued by the DMA function that are claimed by the PCI-to-
PCI bridge function in the upstream port are routed as described in the previous example. TLPs
issued by the DMA function that are claimed by the NT function (i.e., the TLP falls into one of the
NT function’s memory windows) are routed across the non-transparent interconnect and emitted
by the NT function in the target partition.
In such a configuration, programming of the DMA would be typically done by an agent (e.g., the CPU) in
the partition on which the DMA resides.
1
This would allow the programming agent to ‘push’ data from its
partition to another partition, or ‘pull’ data from another partition into its partition. If symmetry is desired, the
upstream port in both partitions could be programmed to have a DMA function, as shown in Figure 1.14.
This allows agents in either partition to push or pull data from the other partition.
Figure 1.13 Two Switch Partitions Interconnected by an NTB, with DMA in One Partition
1.
In the switch, the DMA may be programmed by agents that are not in the partition on which the DMA function
resides. This is done by accessing the PES32NT24xG2’s global address space (see Chapter 19 for details).
Partition 0 – Virtual PCI Bus
P2P
Bridge
Upstream
Port
P2P
Bridge
P2P
Bridge
Downstream Ports
Non-Transparent
Interconnect
Upstream
Port
NT
Endpoint
NT
Endpoint
DMA
Function