Constrained signal selection for post-silicon validation

Limited signal observability is a major concern during post-silicon validation. On-chip trace buffers store a small number of signal states every cycle. Existing signal selection techniques are designed to select a set of signals based on the trace buffer width. In a real-life scenario, it is reasonable that a designer has determined some important signals that must be traced. In this paper, we study the constrained signal selection problem where a set of trace signals are already provided by the designer and the remaining signals have to be determined to improve overall restoration performance. Our experimental results using ISCAS'89 benchmarks demonstrate that up to 5% improvement can be obtained in restoration performance compared to existing approaches.