Automated Replacement of State-Holding Flip-Flops to Enable Non-Volatile Checkpointing

Applications in safety-critical areas like automotive or aerospace require functions to handle system failures. A commonly used technique on different system levels is checkpointing, which enables a rollback in such an event. However, at register level, power failures cause CMOS flip-flops to lose data, requiring a complete reboot instead of a fast rollback.In this paper, we propose the use of hybrid volatile/non-volatile flip-flops to prevent data loss on power shortages. To reduce the area overhead introduced by those, we present our automated toolchain based on open-source tools to find potential state-holding flip-flops in a netlist and implement those as hybrid volatile/non-volatile for checkpointing. This approach not only reduces area overhead and improves resiliency, but also enables aggressive power-gating strategies to increase energy efficiency.Exemplary, we test our toolchain for three RISC-V based processors and verify our results in simulation. Thereby, we can show that our proposed approach is able to determine all state-holding flip-flops in each architecture.