The major_rc return value from the exectu() function should indicate the success or failure of the TU which was executed. If all testing is successful, it should return a value of zero (0), otherwise a non-zero value should be returned corresponding to a specific value. A managing application uses the major_rc return code to determine the flow of the diagnostic procedure, and to look up the appropriate card level Field Replaceable Unit (FRU) or FRUs to be replaced. To satisfy the failure-isolation requirements of all managing applications, the return codes should be designed to be as granular as possible to provide maximum fault isolation. For most purposes, this means attempting to isolate to a single FRU.
Attention: When defining major_rc return codes, keep the following in mind:
The minor_rc return value is used to pass back a more specific error indication, and would typically be provided as an aid for fault isolation within a FRU, perhaps down to modules or I/O lines. This information is intended for use in bring-up and debug, and in manufacturing, to point to a specific hardware defect. Used in conjunction with the OUTPUT_DATA error log, the TU writer should be able to pass back enough information to isolate to a failure to whatever level is needed. However, most management applications will only be interested in the major_rc return value.