# riscv-formal-nmigen

A port of [riscv-formal](https://github.com/SymbioticEDA/riscv-formal) to nMigen

## Breakdown

| File/Directory | Description |
| --- | --- |
| `shell.nix` | [nix-shell](https://nixos.wiki/wiki/Development_environment_with_nix-shell) configuration file |
| `rvfi` | RISC-V Formal Verification Framework (nMigen port) |
| `rvfi/insns` | Supported RISC-V instructions and ISAs |
| `rvfi/checks` | Checks for RISC-V compliant cores |
| `rvfi/cores` | Cores currently tested against this port of riscv-formal |
| `rvfi/cores/minerva/verify.py` | Verification tasks for the Minerva core |

## Running the Verification

First make sure you have [Nix](https://nixos.org/download.html) installed. Then `cd` to the root directory of this repo and run:

```bash
$ nix-shell
```

This should run the tests (cache, multiplier, divider) provided by Minerva itself and give you an environment with all the dependencies required for this project. Then, to run the main verification tasks for Minerva provided in this repo:

```bash
$ python -m rvfi.cores.minerva.verify
```

This should run in the order of a few hours.

## Scope

The RV32I, RV32M, RV64I and RV64M ISAs are currently implemented but only RV32IM are being tested by integrating with the Minerva core.

## Possible improvements

In no particular order:

- Combine individual instruction checks into single ISA check (currently, doing so takes forever even when depth is set to only `20`)
- Parallelize execution of verification tasks to reduce the total time required to run all verification tasks on a multi-core system

## License

See [LICENSE](./LICENSE)