IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 51 / 744

IDT PES32NT24xG2 Device Overview
PES32NT24xG2 User Manual 1 - 15 January 30, 2013
Notes
Figure 1.14 Two Switch Partitions Interconnected by an NTB, with DMA in Both Partitions
DMA transfers are always memory-mapped, and can therefore leverage the multicast feature offered by
the PES32NT24xG2 (see section Multicasting and Non-Transparent Multicasting on page 1-17 for an intro-
duction to Multicast support in the switch). The DMA function can be programmed to read data from a
source memory-mapped location, and issue a multicast write operation to transfer the data to several
memory-mapped destination locations in one shot. As described in section Multicasting and Non-Trans-
parent Multicasting on page 1-17, the data can even be multicasted across switch partitions. The switch’s
DMA operation is described in detail in Chapter 15, DMA Controller.
Dynamic Reconfiguration and Failover
Dynamic reconfiguration refers to the modification of the PES32NT24xG2 switch configuration at
runtime (i.e., after fundamental reset). The switch supports two forms of dynamic reconfiguration. The first
is reconfiguration of the ports associated with a switch partition. The second is reconfiguration of the oper-
ating mode of a port. Partition and port reconfiguration may be initiated by software executing on a root
complex or SMBus master, or initiated by hardware as the result of a failover event. The switch supports
four failover configuration structures. Each configuration structure may be independently configured to
initiate a failover event on:
– a configuration register write,
– watchdog timer time-out, or
– external device pin state transition.
An example failover operation is illustrated in Figure 1.15. Figure 1.15(a) illustrates a possible
PES32NT24xG2 application with two partitions. Partition zero represents a transparent switch while parti-
tion one is an NT port with an alternate (secondary) root. The primary upstream port is able communicate
with I/O device on downstream switch ports in a transparent manner. The primary upstream port is able to
synchronize failover state information (e.g., recovery point data) with the secondary upstream port using the
NT endpoints and non-transparent interconnect. Although not shown in Figure 1.15, it is possible to use the
PES32NT24xG2’s DMA function to off-load the root processor from this task. Downstream I/O devices are
able to transfer data to the primary root and to the secondary root.
Partition 0 – Virtual PCI Bus
P2P
Bridge
Upstream
Port
P2P
Bridge
P2P
Bridge
Non-Transparent
Interconnect
Upstream
Port
Partition 1 – Virtual PCI Bus
P2P
Bridge
P2P
Bridge
P2P
Bridge
NT
Endpoint
NT
Endpoint
DMA
Function
DMA
Function
Downstream Ports Downstream Ports