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Getting Started with FlooNoC

This guide covers how to set up the environment to simulate and verify the FlooNoC hardware IPs (SystemVerilog). If you are looking to generate a network configuration, please refer to the FlooGen documentation.

Prerequisites

1. Bender

FlooNoC uses Bender for hardware IP management and dependency handling. Bender is available as pre-compiled binaries for Linux, macOS, and Windows (or can be installed via Cargo).

curl --proto '=https' --tlsv1.2 https://pulp-platform.github.io/bender/init -sSf | sh

cargo install bender

Note

Ensure the Bender binary is in your PATH, or set the BENDER environment variable to point to it.

Then you can check whether Bender is installed correctly by fetching the dependencies:

bender checkout

This is not strictly necessary since subsequent Make commands will perform this step automatically, but it is useful to verify that Bender is set up correctly.

2. Simulation Tools

The testbenches provided with FlooNoC are designed to be run with QuestaSim and VCS.

Note

Other simulators might work, but are not officially supported. Verilator is known to have issues with testbench components that use advanced SystemVerilog features.

Installation

Clone the repository to get the hardware IPs and verification environment:

git clone https://github.com/pulp-platform/FlooNoC.git && cd FlooNoC

Running Simulations

We provide a Makefile to simplify compiling and running the testbenches.

1. Compile the Hardware

Compile the RTL and testbenches:

make compile-vsim

make compile-vcs TB_DUT=<testbench_name>

2. Run a Testbench

You can run specific testbenches by setting the TB_DUT variable:

make run-vsim TB_DUT=<testbench_name>

or in batch mode:

make run-vsim-batch TB_DUT=<testbench_name>

make run-vcs TB_DUT=<testbench_name>

Available Testbenches

You can substitute <testbench_name> with other testbenches found in hw/tb/:

Testbench Description
tb_floo_router Verifies a single router instance.
tb_floo_axi_chimney Verifies the AXI-to-NoC network interface.
tb_floo_nw_mesh Simulates a small mesh network of routers.
tb_floo_rob Simulates out-of-order buffer behavior.

Advanced mesh testbenches

There are additional testbenches for entire mesh networks:

Testbench Description
tb_floo_axi_mesh Simulates a full mesh network with single-AXI endpoints.
tb_floo_nw_mesh Simulates a full mesh network with narrow-wide AXI endpoints.

Those testbenches require generated networks from FlooGen. Please refer to the FlooGen documentation for instructions on how to install FlooGen.

Generating Mesh Testbenches

Then, you can generate either of the testbenches with:

uv run floogen rtl -c floogen/examples<mesh>_<route_algo>.yml -o generated

floogen rtl -c floogen/examples<mesh>_<route_algo>.yml -o generated

Where <mesh> is either axi_mesh or nw_mesh, and <route_algo> is either xy, id or src.

Compiling Testbenches

Then, you can compile and run the generated testbenches as described above, with additional Bender flags to include the generated files:

make compile-vsim EXTRA_BENDER_FLAGS="-t <mesh>"

# Currently not supported

Generating Traffic

The endpoint of those testbenches are DMA models that accept job files to perform AXI transactions over the network. This is better documented in the DMA documentation here. There is a script util/gen_jobs.py that can help generate job files for testing.

For instance you can generate random traffic with:

make jobs DUT=<mesh> ROUTE_ALGO=<route_algo> TRAFFIC_TYPE=<traffic_type> TRAFFIC_RW=<read_or_write>

Currently supported traffic types are:

Traffic Type Description
hbm Traffic goes to boundary nodes (simulating HBM).
uniform Traffic is uniformly distributed across all nodes.
onehop Each node accesse its upper neighbor.
bit_complement Each node accesses its bit-complement address.
bit_reverse Each node accesses its bit-reversed address.
bit_rotation Each node accesses its bit-rotated address.
neighbor Each node accesses one of its neighbors (X-direction).
shuffle Each node accesses another node in a shuffled manner.
transpose Each node accesses another node in a transposed manner.
tornado Each node accesses a node halfway across the network.
hotspot Traffic goes to a single hotspot node.
hotspot_boundary Traffic goes to a single hotspot node on the boundary.

Running Mesh Testbenches

You can run the generated testbenches with:

make run-vsim TB_DUT=tb_floo_<mesh> EXTRA_BENDER_FLAGS="-t <mesh>"

# Currently not supported