In-band Cross-Trigger Event Transmission for Transaction-Based Debug

Cross-trigger, the mechanism to trigger activities in one debug entity from debug events happened in another debug entity, is a very useful technique for debugging applications involving multiple embedded cores. Existing solutions rely on dedicated interconnects (i.e., different from functional interconnects) to transfer debug events and cannot guarantee the arrival time of the debug events coincides with the arrival time of the data messages between multiple cores. This results in mismatches between the observed system internal operations and the ones that designers expect to watch. To tackle the above problem, in this paper, we propose to package the cross-trigger events and the actual data together into transaction messages and transfer them along the same functional interconnects (namely in- band debug event transmission), with the help of novel design-for- debug circuits. Simulation results on a hypothetical NoC-based systems show the effectiveness of the proposed technique.