
IDT Switch Core
PES32NT24xG2 User Manual
4 - 19
January 30, 2013
Notes
As the TLP flows through the switch, its alignment or contents may be modified. In all such cases, parity
is updated and not recomputed. Hence, any error that occurs is propagated and not masked by a parity
regeneration. When the TLP reaches the DL layer of the switch egress port, parity is checked and in parallel
an LCRC is computed. If the TLP is parity error free, then the LCRC and TLP contents are known to be
correct and the LCRC is used to protect the packet through the lower portion of the DL layer, PHY layer, and
link transmission.
If a parity error is detected by the DL layer of an egress port, then the TLP is nullified by inverting the
computed LCRC and ending the packet with an EDB symbol. Nullified TLPs received by the link-partner are
discarded. In addition to nullifying the TLP, the End-to-End Parity Error (E2EPE) bit is set in the Internal
Error Status 0 (IERRORSTS0) register.
The DL layer never replays a TLP with a sequence number different from that
initially used. If a parity error is detected during a DL layer replay, then all TLPs in the
replay buffer are flushed.
In addition to TLPs that flow through the switch, cases exist in which TLPs are produced and consumed
by the switch (e.g., configuration requests that target a function in the switch, TLPs that target a DMA func-
tion, requests and completions generated by a switch function, etc.) Whenever a TLP is produced by the
switch, parity is computed as the TLP is generated. Thus, error protection is provided on produced TLPs as
they flow through the switch. In addition, parity is checked on all consumed TLPs. If an error is detected, the
TLP is discarded and an error is reported by setting the E2EPE bit in the IERRORSTS0 register.
A parity error reported at a switch port cannot be definitively used to identify the location within the
device at which the fault occurred as the fault may have occurred at another port, in the switch core, or may
have occurred locally at the port.
Reporting of Port AER Errors as Internal Errors
In scenarios in which the PES32NT24xG2 switch is multi-partitioned, a need may exist to inform the root
associated with each partition of anomalous conditions occurring in ports associated with other partitions.
For example, a root acting as a switch manager may have a need to be notified of a surprise link down
condition in a port associated with another switch partition. The switch manager could use this information
to reconfigure the switch.
The event signaling mechanism described in Chapter 16, Switch Events, provides this capability by
allowing events in a partition to be notified to root devices in other partitions via interrupts generated by
each partition’s upstream port. Still, the event signaling mechanism is limited to notifying partitions of a
number of pre-defined events (e.g., port link down, port link up, failover, etc.), which do not include port AER
errors.
In order to notify a partition of the occurrence of port AER errors in other partitions, the switch offers a
mechanism by which AER errors that occur in a port (e.g., ACS violation, receiver overflow, etc.) may be
reported as internal errors in the AER Capability Structure of any other port. In this case, the port(s) in
which the error is logged as an AER internal error report the error to the system as defined by AER rules
(i.e., an uncorrectable fatal, non-fatal, or correctable error message may be generated by the port).
As mentioned above, each port contains internal error detection logic that feeds into the port’s Internal
Error Status (IERRORSTS0/1) registers as well as the AER internal error status bits (see Figure 4.7). Apart
from detecting internal errors in the port itself, the internal error detection logic of a port is capable of
noticing when other ports have detected an AER error.
When the internal error detection logic in a port notices the occurrence of an AER error in another port,
a bit is set in the IERRORSTS1 register of the former port. The IERRORSTS1 register has several bits
(e.g., P0AER, P1AER, P2AER, etc.) Bit PxAER is set when port ‘x’ has notified the detection of an AER
error as described next.
Содержание PCI Express 89HPES32NT24xG2
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Страница 124: ...IDT Switch Partition and Port Configuration PES32NT24xG2 User Manual 5 24 January 30 2013 Notes...
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Страница 164: ...IDT SerDes PES32NT24xG2 User Manual 8 16 January 30 2013 Notes...
Страница 170: ...IDT Power Management PES32NT24xG2 User Manual 9 6 January 30 2013 Notes...
Страница 196: ...IDT Transparent Switch Operation PES32NT24xG2 User Manual 10 26 January 30 2013 Notes...
Страница 244: ...IDT SMBus Interfaces PES32NT24xG2 User Manual 12 40 January 30 2013 Notes...
Страница 247: ...IDT General Purpose I O PES32NT24xG2 User Manual 13 3 January 30 2013 Notes...
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Страница 330: ...IDT Switch Events PES32NT24xG2 User Manual 16 6 January 30 2013 Notes...
Страница 342: ...IDT Multicast PES32NT24xG2 User Manual 17 12 January 30 2013 Notes...
Страница 344: ...IDT Temperature Sensor PES32NT24xG2 User Manual 18 2 January 30 2013 Notes...
Страница 384: ...IDT Register Organization PES32NT24xG2 User Manual 19 40 January 30 2013...
Страница 492: ...IDT Proprietary Port Specific Registers PES32NT24xG2 User Manual 21 44 January 30 2013 Notes...
Страница 588: ...IDT NT Endpoint Registers PES32NT24xG2 User Manual 22 96 January 30 2013 Notes...
Страница 710: ...IDT JTAG Boundary Scan PES32NT24xG2 User Manual 25 12 January 30 2013 Notes...
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