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RISC-V processor IPs are increasingly being integrated into system-on-chip designs for a variety of applications. However, there is still a lack of dedicated functional verification solutions supporting high-integrity, trusted integrated circuits. This paper examines an efficient, novel, formal-based RISC-V processor verification methodology. The RISC-V ISA is formalized in a set of Operational SystemVerilog assertions. Each assertion is formally verified against the processor’s RTL model. Crucially, the set of assertions is then mathematically proven to be complete and free from gaps, thus ensuring that all possible RTL behaviors have been examined. This systematic verification process detects both deliberate hardware Trojans and genuine functional errors present in the RTL code. The solution is demonstrated on an open-source RISC-V implementation using a commercially available formal tool, and is arguably a significant improvement to previously published RISC-V ISA verification approaches, advancing hardware assurance and trust of RISC-V based designs.
Connectivity checking is a popular formal verification application. Formal tools can automatically generate assertions using a specification table as input and prove them exhaustively. Simulation-based verification, on the other hand, requires significantly more effort while providing a fraction of the coverage. However, chip complexity is rapidly increasing. ASICs and FPGAs for heterogeneous computing, 5G, AI, and ML applications have hundreds of thousands of deep connections to verify. The computational challenge is enormous. Furthermore, creating the connectivity specification is a time-consuming, error-prone task. The most recent papers on formal connectivity checking report results on designs of up to 200 million gates, with up to 132 thousand connections proven. This paper presents an innovative approach to addresses both specification and computational challenges, and scale formal connectivity checking to previously intractable problems. Results are reported on a multi-billion-gate SoC fabric in the latest technology node with over 1 million connections to specify and verify.
Formal verification becomes the method of choice for designs with stringent quality requirements. For complex architectures with many implementation alternatives, however, the development and maintenance of complete formal specifications remains a challenge. In this work, we present an efficient semi-formal specification approach for processor designs with a large number of architectural variants.
Complete Formal Verification of TriCore2 and Other Processors
This paper describes an innovative and powerful methodology for the complete formal verification of modules and intellectual property (IP), and its application to the verification of processor IP. Unlike other formal approaches, the methodology is a self-contained approach to hardware verification, independent of simulation.