Showcase for lowRISC Ibex integration into SimBricks

This repository contains all the necessary pieces for a simple integration of the lowRISC Ibex into SimBricks.

This includes:

• A memory adapter for the Ibex core using the simple memory protocol of SimBricks
• Integration of the Ibex core into the orchestration framework of SimBricks
• An application based on Ibex's simple_system example, that prints characters on a terminal
• A virtual prototype configuration script that connects the Ibex core with memory and a simple terminal simulator and runs the application

Getting started

You can run the virtual prototype either via our demo or locally on your machine.

SimBricks demo

After creating a SimBricks demo account you can open the devcontainer that is provided with this repository. In the devcontainer you just need to submit the virtual prototype configuration using the already installed simbricks-cli command:

simbricks-cli runs submit -f virtual_prototype.py

Instead of the devcontainer you can also install the necessary SimBricks Python packages locally (see requirements.txt). For more information on that you can also look at the README.md in the simbricks-examples repository.

Local

In order to run the virtual prototype configuration locally, the easiest approach is to use the docker image provided by the Dockerfile in this repository. For this, build the docker image first, for example with the following command:

docker build -t showcase-ibex:latest .

This will

• build Ibex including our SimBricks adapter with Verilator
• build the application
• install the necessary SimBricks Python packages
• put the relevant files under /lowrisc-ibex
• have SimBricks with pre-built simulators under /simbricks

Now you can spin up a docker container and run the virtual prototype configuration:

docker run --rm -it --entrypoint /bin/bash showcase-ibex:latest
> cd /lowrisc-ibex
> simbricks-run --verbose virtual_prototype.py

Virtual prototype configuration overview

The python script virtual_prototype.py contains a virtual prototyping configuration that runs the system as shown in the figure above. The configuration runs the Ibex core using Verilator including our adapter, a basic memory device simulator, a simple memory terminal simulator, and a memory interconnect simulator. The memory interconnect connects the Ibex core with the memory device and the terminal. All connections are SimBricks channels using the simple memory protocol provided by SimBricks.

When executing the configuration, first the binary of the application is loaded into the memory device and then the Ibex core starts reading the instructions from the memory and executes them. During the execution the Ibex core writes output to the terminal simulator, which prints the output to the simulation output.

This serves as a simple first example, but of course it can be easily extended. For example, other simulators that implement the memory interface can be connected through SimBricks channels to the Ibex core in the same way as the memory device and the memory terminal.