Application Level Hardware Tracing for Scaling Post-Silicon Debug

We present a method for selecting trace messages for post-silicon validation of Systems-on-a-Chips (SoCs) with diverse usage scenarios. We model specifications of interacting flows in typical applications. Our method optimizes trace buffer utilization and flow specification coverage. We present debugging and root cause analysis of subtle bugs in the industry scale OpenSPARC T2 processor. We demonstrate that this scale is beyond the capacity of current tracing approaches. We achieve trace buffer utilization of 98.96% with a flow specification coverage of 94.3% (average). We localize bugs to 21.11% (average) of the potential root causes in our large-scale debugging effort.