# 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
```

## 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:

- Allow configurable limit for no. of running processes in order to prevent thrashing
- Combine individual instruction checks into single ISA check (currently, doing so takes forever even when depth is set to only `20`)

## License

See [LICENSE](./LICENSE)