The Enable Error Classification check box is used to enable or disable the error classification feature. Error classification is available in the mitigation modes (Mitigation and Testing or Mitigation only) where error correction is enabled.
The error classification feature uses the AMD Essential Bits technology to determine whether a detected and corrected soft error has affected the function of a user design.
Essential Bits are those bits that have an association with the circuitry of the design. If an Essential Bit changes, it changes the design circuitry. However, it might not necessarily affect the function of the design.
Without knowing which bits are essential, the system must assume any detected soft error has compromised the correctness of the design. The system-level mitigation behavior often results in disruption or degradation of service until the FPGA configuration is repaired and the design is reset or restarted.
For example, if the Vivado Bitstream Generator reports that 20% of the configuration memory is essential to an operation of a design, only two out of every 10 soft errors (on average) actually merits a system-level mitigation response. The error classification feature is a table lookup to determine if a soft error event has affected essential configuration memory locations. Use of this feature reduces the effective FIT of the design. The cost of enabling this feature is the external storage required to hold the lookup table.
When error classification is enabled, the Fetch Interface is generated (as indicated by the Component Symbol) so that the controller has an interface through which it can retrieve external data. For the delivered example design, the Fetch Interface needs to be bridged to an external SPI flash. Additionally, a SPI flash master helper is included in the example design to enable this connection.
If error classification is enabled, and a detected error has been corrected, the controller looks up the error location. Depending on the information in the table, the controller either reports the error as essential or non-essential. If a detected error cannot be corrected, this is because the error cannot be located. Therefore, the controller conservatively reports the error as essential because it has no way to look up data to indicate otherwise.
If error classification is disabled, the controller unconditionally reports all errors as essential because it has no data to indicate otherwise.