IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 328 / 744

IDT Switch Events
PES32NT24xG2 User Manual 16 - 4 January 30, 2013
Notes
Global Signals
Global signals allow an agent in a switch partition to signal a switch event. This mechanism provides a
primitive form of communication that allows an agent in a switch partitition to communicate with agents in
other partitions. Such communication may be used to coordinate actions such as dynamic partition re-
configuration by a switch management agent.
– A global signal event may be signaled by an NT function by writing a one to the Global Signal
(GSIGNAL) bit in the NT Endpoint Global Signal (NTGSIGNAL) register.
– A global signal event may be signaled by an upstream PCI-to-PCI bridge by writing a one to the
Global Signal (GSIGNAL) bit in the PCI-to-PCI Bridge Global Signal (P2PGSIGNAL) register.
Associated with each partition is a global signal status bit in the Global Switch Event Signal Status
(SEGSIGSTS) register. When a global signal is issued by an agent in a switch partition, the corresponding
partition bit in this register is set.
Associated with each status bit in the SEGSIGSTS register is a mask bit in the Switch Event Global
Signal Mask (SEGSIGMSK) register. When an unmasked status bit is set in the SEGSIGSTS register, the
Global Signal (GSIGNAL) status bit is set in the Switch Event Status (SESTS) register.
Figure 16.2 shows the global signaling mechanism. As shown, any partition can issue a global signal,
which is logged in a corresponding bit in the SEGSIGSTS register. This feeds into the registers that control
event signaling (i.e., SESTS, SEMSK, SEPMSK), thereby allowing the signaling of a switch event in any
partition.
Figure 16.2 Global Signaling Mechanism
Registers associated with global signal events are located in the NT function and the PCI-to-PCI bridge
function of a partition’s upstream port. These registers provide a complementary communication mecha-
nism for the global signals mechanism. The manner and protocol used for this communication is beyond the
scope of this specification. For example, an agent that issues a global signal event may use these registers
to store information regarding the reason behind the issuing of the global signal event.
Event
Signaling
to partition
Switch
SESTS Register
SEMSK Register
SEPMSK Register
Partition 1 Partition 7
Registers that
control Switch
Event Signaling
Event
Signaling
to partition Event
Signaling
to partition
SEGSIGMSK Register
SEGSIGSTS Register
P2P
Bridge
P2P
Bridge
P2P
Bridge
Global Signals
Status & Mask
Global Signal