Post Silicon Debugging of Electrical Bugs Using Trace Buffers

Abstract

Post-silicon debug is the task of finding the bugs that could not be found before manufacturing. Electrical bugs are an important category of post-silicon bugs that are typically hard to debug due to complex interdependence of layout and netlist as well as their dependency to the running workload and environment. In this paper, we tackle the problem of debugging electrical bugs using trace buffers. Given an erroneous values captured in the trace buffer due to occurrence of an electrical bug, we try to identify the spatial and temporal location of the error. We have formulated the problem of debugging electrical bugs as a SAT problem and proposed a debugging method based on that. Moreover, we have shown that the existing signal selection methods for logical bugs that are typically trying to maximize signal restoration ratio (SRR) metric, do not perform better than random selection when debugging electrical bugs. On the other hands, utilizing a more sophisticated signal selection that is considering propagation of bit-flips due to electrical bugs is more effective.