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Link Layer — Intel
®
82575EB Gigabit Ethernet Controller
324632-003 Intel
®
82575EB Gigabit Ethernet Controller
Revision: 2.1 Software Developer’s Manual and EEPROM Guide
January 2011 185
2. Changes in the response to some Uncorrectable Non-Fatal errors detected in non-posted requests
to the 82575 called Advisory Non-fatal Error cases. For each of the errors listed, the following
behavior is defined:
a. The Advisory Non-Fatal Error Status bit is set in the Correctable Error Status register to indicate
the occurrence of the advisory error, and the Advisory Non-Fatal Error Mask corresponding bit in
the Correctable Error Mask register is checked to determine whether to proceed further with
logging and signaling.
b. If the Advisory Non-Fatal Error Mask bit is clear, logging proceeds by setting the corresponding
bit in the Uncorrectable Error Status register, based upon the specific uncorrectable error that is
being reported as an advisory error. If the corresponding uncorrectable error bit in the
Uncorrectable Error Mask register is clear, the First Error Pointer and Header Log registers are
updated to log the error, assuming they are not still occupied by a previously unserviceable error.
c. An ERR_COR Message is sent if the Correctable Error Reporting Enable bit is set in the Device
Control register. An ERROR_NONFATAL message is not sent for this error.
The following Uncorrectable Non-Fatal errors are considered as Advisory Non-fatal Errors:
• A Completion with an Unsupported Request or Completer Abort (UR/CA) Status that signals an
uncorrectable error for a Non-Posted Request. If the severity of the UR/CA error is non-fatal, the
Completer must handle this case as an Advisory Non-Fatal Error.
• When the Requester of a Non-Posted Request times out while waiting for the associated
Completion, the Requester is permitted to attempt to recover from the error by issuing a separate
subsequent Request or to signal the error without attempting recovery. The Requester is permitted
to attempt recovery zero, one, or multiple (finite) times, but must signal the error (if enabled) with
an uncorrectable error Message if no further recovery attempt is made. If the severity of the
Completion Timeout is non-fatal, and the Requester elects to attempt recovery by issuing a new
request, the Requester must first handle the current error case as an Advisory Non-Fatal Error.
• When a Receiver receives an unexpected Completion and the severity of the Unexpected
Completion error is non-fatal, the Receiver must handle this case as an Advisory Non-Fatal Error.
6.5 Link Layer
6.5.1 ACK/NAK Scheme
The 82575 supports two alternative schemes for ACK/NAK rate:
1. ACK/NAK is scheduled for transmission according to timeouts specified in the LTIV register.
2. ACK/NAK is scheduled for transmission according to time-outs specified in the PCIe* Specification.
The ACK/NAK scheme bit loaded from the EEPROM determines which of the two schemes is used.
6.5.2 Supported DLLPs
The following DLLPs are supported by the 82575 as a receiver.
Table 59. DLLPs Received
Ack
Nak
PM_Request_Ack