No SoC verification engineer worthy of the title would argue that coverage is unimportant. Even back in the 1980s, before commercial coverage tools and industry standards were available, leading ASIC teams manually added coverage code into their testbenches. They checked that key state machines visited all legal states or made all legal transitions, or that a processor executed all opcodes in its instruction set, over the course of a simulation test.
Verification teams who ignored coverage in those days were at risk of letting bugs slip through to silicon. The old maxim “if you don’t verify it, it’s broken” summed the situation up well. Today, leading SoC teams have adopted system coverage. Those who are ignoring this aspect of coverage are at risk of letting serious system-level bugs slip through. Let’s talk about system coverage and why it’s different from other metrics in use today.