Verilator Example

Intro

This project ties together a few interesting technologies:

• verilator
• SystemVerilog (for DUT & TB)
• C/C++ (for TB & DUT)
• Buck2 (for building)
• TODO: rust (for TB & DUT, maybe sim_main/wrapper/cmd-line-processing)

Repo

Cloning w/ Submodules

git clone --recurse-submodules https://github.com/yangm2/verilator-example.git

Pull repo

git pull --recurse-submodules

Components

DUT

• counter
• valid-interface (TODO: add flow-control/back-pressure)

Testbench

• collector + monitor - demonstrate SV+VPI(C/C++)
• driver + sequencer - demonstrate SV+VPI(C/C++) for pipelined interface (TODO: add flow-control/back-pressure)

Commands

• Clean:

  • buck2 clean

• Compile:

  • buck2 build //src:Vhello_world

• Run:

  • buck2 run :sim101 # root-level alias with hard-coded args that reaches into ./src
  • buck2 run //src:sim100 # alias with hard-coded args
  • buck2 run //src:Vhello_world +MAX_CYCLES=23

Maintenance

Buck2

• prelude submodule version needs to match (or be behind?) the corresponding installed buck2 version
  1. buck2 --version -- doesn't actually tell you anything useful for nix-managed installs
  2. ./utils/get-nix-buck2-prelude_hash.py ...

  Reading inline script metadata from `./update-buck2-prelude.py`
  nix installed version of unstable 'buck2' is [2024-10-15] at [/Users/michaelyang/.nix-profile/bin/buck2]
  corresponding 'prelude_hash' is [615f852ad43a901d8a09b2cbbb3aefff61626c52]

  3. in repo ...

  cd prelude
  git pull
  git checkout $__prelude_hash_FROM_ABOVE__
  cd `git rev-parse --show-toplevel`
  git add prelude
  git commit -m 'bump buck2-prelude submodule for buck2 $__UNSTABLE_VERSION_FROM_ABOVE__'
  git push