Explicit Yosys Plugin Handling

[hpretl]

Description

A user tried to use the VHDL flow in OpenLane in our IIC-OSIC-TOOLS image, see iic-jku/IIC-OSIC-TOOLS#43.

The error is that the command ghdl is not working inside Yosys. If I start Yosys just by

> yosys

then running ghdl inside, it throws the error ERROR: No such command: ghdl (type 'help' for a command overview).

If I start Yosys with

> yosys -m ghdl

then running ghdl inside Yosys works fine!

Question: What is wrong with the OpenLane setup in our image?

Expected Behavior

VHDLClassic flow should work.

Environment report

Failed to get Docker info: [Errno 2] No such file or directory: 'docker'
Failed to get Nix info: [Errno 2] No such file or directory: 'nix'
kernel: Linux
kernel_version: 6.6.32-linuxkit
supported: True
distro: ubuntu
distro_version: 22.04
python_version: 3.10.12
python_path:
  - /usr/local/lib/python3.10/dist-packages/openlane
  - /headless/.local/lib/python3.10/site-packages
  - /usr/lib/python310.zip
  - /usr/lib/python3.10
  - /usr/lib/python3.10/lib-dynload
  - /usr/local/lib/python3.10/dist-packages
  - /usr/lib/python3/dist-packages
  - /usr/lib/python3.10/dist-packages
  - /foss/tools/ngspyce/154a272/local/lib/python3.10/dist-packages
  - /foss/tools/pyopus/0.11/local/lib/python3.10/dist-packages
  - /foss/tools/yosys/share/yosys/python3
  - /foss/tools/klayout/v0.29.4/pymod
tkinter: True
container_info: None
nix_info: None

Reproduction material

None needed.

Relevant log output

See above.

[hpretl]

@donn Maybe the above issue just boils down to the question: How is OpenLane calling yosys, and how do you load modules like ghdl?

[hpretl]

I don't understand nix, but it looks like there is some kind of wrapper involved? https://github.com/efabless/openlane2/blob/7691a45f4bbafc77ab70f30c22d9698d462e41c7/nix/yosys.nix

[donn]

@hpretl That's correct. We wrap the Yosys binary to load the modules, including GHDL and Lighter (upstream Nixpkgs does this as well too.)

Something like this in place of the yosys binary should work:

#!/bin/sh
exec -a "$0" <path/to/yosys-bin> -m ghdl "$@"

[hpretl]

We implemented now a wrapper similar to the above one in our IIC-OSIC-TOOLS. An alternative way, I think cleaner, is that OpenLane adapts the calling of yosys. Like using yosys for Verilog, or using yosys -m gdhl for VHDL, or yosys -m systemverilog.

Or just use yosys -m ghdl -m systemverilog in any case, if this modules are available.

@donn What do you think?

[donn]

Doable- will think about it, I'm messing with Yosys stuff atm

[hpretl]

Please notify me when you change things because then I will remove the Yosys wrapper again :-)

[donn]

2.2.0 loads plugins explicitly, however, it introduces another issue because you need to pull in YosysHQ/yosys#4553 until it gets merged

Anyways, should be in the next release. Thank you for your patience