2.9.2 Error detection, signaling, and reporting

Each CCN-502 block that connects to a configuration bus can be included in the local error reporting mechanism.

The error handling protocol is as follows:

Error signaling

When the MN captures an error signal, the signal is sticky and is only cleared by the error handler reading the Error Signal Valid registers in the MN.

Error logging

Each CCN-502 component records the details of the error in the Error Syndrome registers.

The number of Error Syndrome registers is either 1 or 2 depending on the amount of information the component must log:

  • An XP uses one Error Syndrome register to log parity errors.
  • The HN-I and HN-F use two Error Syndrome registers each.

The following fields in the Error Syndrome registers are used:

err_extndExtended. Set to 1 if the error log information extends into a second Error Syndrome register or beyond.
first_err_vldFirst error valid. Set to 1 when an error is first logged.
err_class

First error classification. The error is classified into one of the three predefined error classes. See the following table.

Table 2-2 Error classification field encoding

Error class [1:0] Field
00 Reserved
01 Correctable
10 Reserved
11 Fatal
mult_errMultiple errors. More than one error is seen.
corrected_err_countCorrected Error Count. A saturating counter with up to 16 bits to count corrected errors.
component_specific_reg0,component_specific_reg1Component Specific. These fields are reserved for component-specific error logging. For packet errors, the complete control portion of the packet can be stored in these fields, extended over multiple registers.

Error log clearing

In addition to the Error Syndrome registers, each component has a write-only Error Syndrome Clear register.

Write the applicable mask bits to clear the first_err_vld and mult_err bits of the Error Syndrome 0 registers.

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