NERV is a very simple single-stage RV32I processor. It is equipped with an RVFI interface and is formally verified.
git clone https://github.com/yosyshq/nerv.git
cd nerv
make
git clone https://github.com/yosyshq/riscv-formal.git
cd riscv-formal/cores/nerv
make -j8 check
From root riscv-formal
directory:
git subtree pull --prefix cores/nerv git@github.com:YosysHQ/nerv.git main --squash
From root riscv-formal
directory:
git subtree push --prefix cores/nerv git@github.com:YosysHQ/nerv.git main
See the iCEBreaker SOC README