User guide

74 www.xilinx.com Virtex-5 FPGA Integrated Endpoint Block
UG197 (v1.5) July 22, 2009
Chapter 4: Integrated Endpoint Block Operation
R
Error Reporting
While failed requests are reported through the completion status field of the completion
packet sent in response to the request, the occurrence of other error conditions is required
by the PCI Express Base Specification to be recorded in the appropriate configuration
registers. In addition, a message advising that an error condition has occurred can
optionally be sent upstream towards the Root Complex. Details of the error condition are
available by reading the relevant fields of the device configuration registers.
As shown in Table 4-3, the integrated Endpoint block performs the error reporting for the
errors shown as being checked. For error checking done by the user, the integrated
Endpoint block offers a range of inputs that can update relevant registers in the event of an
error condition occurring. The error bit(s) set as a result of asserting these signals depends
on both the type of error and the range of extended capabilities configured for the
integrated Endpoint block.
As well as setting the appropriate registers, the assertion of these error signals can also
cause the appropriate in-band
ERR_CORR, ERR_NONFATAL, or ERR_FATAL message to be
sent upstream towards the Root Complex.
The integrated Endpoint block must be reset by the Root Complex after a fatal error is
detected in order to return to normal operation.
Table 4-3 summarizes how different types of errors are reported and handled by the
integrated Endpoint block.
Sequence Number specified by the AckNak_Seq_Num compared with
that of unacknowledged TLPs and value in ACKD_SEQ. If no match
found: (a) the DLLP is discarded; (b) a DLLP error is reported.
3.5.2.1 Required Endpoint block
Checks Made Regarding LCRC and Sequence Number (TLP Receiver)
LCRC field of the received TLP compared with calculated result. If not
equal: (a) the TLP is discarded as corrupt; (b) an error is reported.
3.5.3.1 Required Endpoint block
LCRC field of the received TLP compared with logical NOT of calculated
result if TLP end framing symbol is EDB. LCRC does not match logical
NOT of the calculated value: (a) the TLP is discarded as corrupt; (b) an
error is reported.
3.5.3.1 Required Endpoint block
TLP Sequence Number compared with expected value stored in
NEXT_RCV_SEQ. If not equal, an error is reported.
3.5.3.1 Required Endpoint block
Checks Resulting in Receiver Errors
Validity of received 8B/10B symbols bearing in mind the running
disparity. Errors reported as Receiver Errors.
4.2.1.3 Required Endpoint block
Framing Errors, Loss of Symbol Lock, Lane Deskew Errors, and
Elasticity Buffer Overflow/Underflow. Errors reported as Receiver
Errors.
4.2.2.1 Optional User
Table 4-2: Error Checking Summary (Continued)
PCI Express
Specification
Section
Check is
Required
or Optional
Where Check is
Implemented