This article is an update to Lisa Pipers original posting from April 2011: X-verification: Conquering the “Unknown”
SoCs today are highly integrated, employing many disparate types of IP, running at different clock rates with different power requirements. Understanding the new failure modes that arise from confluences of all these complications, as well as how to prevent them and achieve sign-off, is important. While the issue of handling “X’s” in verification has always been there, it has become more exasperated by low power applications that routinely turn off sections of chips, generating “unknowns”.
Lisa introduces the topic of X-Verification in her DVCon 2012 video interview: