ROHD Dev Tools Extension Proposal

[quekyj]

Summary

A proposal for creating a ROHD debugger that helps user to debug hardware circuitry and design built using ROHD framework.

What problem is this solving?

ROHD is a new framework in Dart to describe and verify hardware development for RTL. However, it posed a challenge for user to debug their design in ROHD due to lack of good UI interface that unable user to:

1. View the module hierarchy, signals of the generated hardware in a tree, like Flutter widget tree.
2. View all the available signals list and possibly perform filter to search for specific signal.
3. Trace signals (drivers and load)
4. View the waveform simulated directly using inbuilt tools.
5. View the hardware schematic designed using ROHD.

Background

ROHD debugger primarily discussed on GitHub issue mentioned here in Dart-Code. Initially, the ideas to extend from VS Code extension instead of extending from flutter dev tools. However, after checking on the dev tools, it seems that dev tools provide more flexibility in interfaces design and all the function available in VS Code extension also provided in dev tool. In another words, whatever can be achieved in VS Code extension can be achieved in dev tool.

Besides, things seem to be even easier as we do not need to learn about the VS Code debug adapter protocol. We can put more focus on implementation with Dart Developer Service (DDS) instead.

Audience

System Verilog Developers, Academic researchers, Students, anyone that uses ROHD as their choices of IC design.

Glossary

• Flutter Dev Tool – A debug tool created by Flutter to help users debug Flutter applications.
• DDS – Dart Developer Services

Non-goals

The scope of this tool will be limited to designs that are fully written using ROHD framework. It does not help in defining System Verilog code that are simulated using co-simulation.

Overview

This proposal aims to design a solution that allows hardware designers to debug and catch bugs easier through interactive UI interface. The following are the expected solutions that should be provided in the debugger itself.

A. Hierarchy Viewer

Priority: High (Request by a lot of developers)
View the module hierarchy and the nested signals inside. It should be something like this. @mkorbel1 did mentioned some interesting stuff on this in Dart-Code/Dart-Code#4589 (comment).

B. Signal Lists

Priority: High

• From the hierarchy viewer, user can filter and check for all the signal lists.
• Double clicking on a signal will navigate user from the signals list tree to waveform viewer and shows which wire is this.

C. Waveform Viewer

Priority: Medium

• Shows the waveform up until the current simulation time.
• User can choose to upload the .vcd file to view on the waveform.

D. Schematic Viewer

Priority: Low

• Schematic view will show the module or block design of the hardware itself.
• Its should work with Simulator that shows the value on the wire during the simulation process.

Usage Examples

Web socket debugging through browser

Users can use the debugger by running the debug in the interactive mode via passing the flag --pause-isolates-on-start --observe. Example, user can run the ROHD dev tool to execute example.dart using the command dart run --pause-isolates-on-start --observe example.dart.

Then, navigate to browser by clicking on the link and it will bring user to the page below.

The current implementation does not have the capabilities of ROHD debuggabilities. Therefore, this project would be about creating ROHD debug tabs for the debug process.

Detailed Design / Discussion

(This part is still under design, and everyone inputs on this part is highly appreciated here)

The following is a detailed description of the recommended approach based on feedback and understanding of the current best practices.

Hierarchy Viewer

• User Story: As a user, I want to identify the module parents and inspect on the respective signals property so that I can easily know which module drives these signals and possibly identify whether there are bugs in the logic when the value on a certain driver is incorrect.
• How does flutter implement the current hierarchy view of widget? Does flutter pull from DDS?
• How to tabulate and show in the flutter UI?
• Can we reuse the same hierarchy view widgets?
• How do we link back or trace back to the source code? Like double click and have [view source] selection.

Signals List

• User Story: As a user, I want to filter and watch for a certain signal during the Simulation
• How to identify variables that are type Logic?
• Experiment with creating a HashMap that maps the logic and its parent module. Then we can easily perform search with O(1) time complexity.

Schematic Viewer

• User Story: As a user, I want to see the schematic diagram of my design so that I can identify the pin connection and verify correctness of my design.
• This would need to think from the UI perspective. Need discussion and review of existing work.
• The feature would need hierarchy viewer and signals list to be completed ahead.
• Ability to trace signals from block to blocks, what is the driver and receivers

Waveform Viewer

This would mean we need to build a widget that can read and output waveform signals in flutter.

• User Story: As a user, I want to view the waveform in my debug tab so that I can save times in installing 3rd party tools just to view my simulated waveform. Also, I want to be able to select signals from the UI (hierarchy, driver/load, schematic, code, etc.) rather than only search by name in a VCD file.
• This would also need to think from the UI perspective. Need discussion and review on existing work.
• How to parse vcd to the UI interface? Probably need to think about this as well.

[zifenglim]

Wowwww, I gain a lot in this page, hope author also can share any related documents or pages for learning purpose!!!

[mkorbel1]

First (beta) version is coming soon! #435