Static verification based signoff - A key enabler for managing verification complexity in the modern soc

Abstract

Summary form only given. Application-based verification, i.e., partitioning the verification process by verification concerns, has become an important approach for managing verification complexity in the billion-transistor SoC. This new verification paradigm has truly come into focus with the proliferation of layers of complexity in an SoC beyond the baseline complexity of its constituent components. In a sense, the nature of chip complexity has shifted from how much goes into a chip to what goes into a chip. Given a narrow verification concern like clock-domain verification, power, dft, reset analysis etc, the specification, analysis and debug dimensions of the verification problem become meaningfully solvable. This is a new paradigm in a sense because it focuses technologists toward the development of complete solutions and closure for the problem at hand as a whole rather than on just nuts-and-bolts technologies like simulation and ABV. Static formal analysis is able to play a key role in this paradigm for various reasons. With the narrow focus on a specific verification problem, much of the specification becomes precise and implicit. In addition, the limited scope allows the formal analysis to be controlled and nominally tractable. Further, even when the formal analysis remains bounded, it is still possible to return actionable information to the user. Finally, debug becomes much more precise and actionable in the context of the narrow verification concern being addressed. These aspects all come to fore in the verification of clock domain crossings in the modern SoC. Used to be that a chip would have a handful of clock domains and the clock-domain checking could be done manually. With 100s of clocks domains on chip, that luxury is not available any more. No SoC gets taped out today without a dedicated sign-off of clock-domain crossings using verification tools specialized for this problem. Another reason clock-domain verification is good to highlight as an example of the new paradigm is that it is at the intersection of chip functionality and timing. This verification task cannot be completed by just functional simulation or just by static timing analysis. It needs a specialized solution, with static formal analysis at its core, to do justice to it.