A Methodology to Capture Fine-Grained Internal Visibility During Multisession Silicon Debug

Silicon debugging is carried out in multiple sessions which are characterized by run-and-halt intervals. One of the important criteria for the success of this method is that the debugging infrastructure should capture only the erroneous data which can add important insights to the debugging process. However, identification of such suspect clock cycles is not a trivial exercise and requires an systematic approach. We propose a debugging architecture for enhancing the multisession procedure using the technique of on-chip debug data compression. The first session assists in identifying those erroneous clock cycles, and the useful debug data are collected in the second session with the help of markers called tag bits. At the cost of a minimal increase in area overhead, the proposed architecture achieves finer temporal visibility expansion because of the debug data collection in a segregated manner. During the offline analysis of the collected debug data, error localization can be achieved to a finer resolution. We evaluate our methodology on several designs for different kinds of error configurations. Experimental results show that the proposed methodology can achieve better on-chip storage utilization and the expansion in the temporal observation window compared to similar techniques in the literature.