SymbiFlow Verilog to XML (V2X)
SymbiFlow Verilog to XML (V2X)

Verilog to Routing XML file generation from Verilog (python-symbiflow-v2x)

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v2x is a tool for converting specialized annotated Verilog models into XML needed for Verilog to Routing flow.

Documentation can be found at


v2x can be installed from a local git repository using pip.

cd python-symbiflow-v2x
pip install .

Alternatively, it can be installed from GitHub directly.

pip install git+


After installing v2x, you can run v2x to use it.

v2x -h
usage: [-h] [--top TOP] [--outfile OUTFILE] [--includes INCLUDES]
                   [--mode {pb_type,model}]
                   input.v [input.v ...]

Verilog to XML

positional arguments:
  input.v               One or more Verilog input files, that will be passed
                        to Yosys internally. They should be enough to generate
                        a flattened representation of the model, so that paths
                        through the model can be determined.

optional arguments:
  -h, --help            show this help message and exit
  --top TOP             Top level module, will usually be automatically
                        determined from the file name im.v
  --outfile OUTFILE, -o OUTFILE
                        Output filename, default 'output.xml'
  --includes INCLUDES   Comma separate list of include directories.
  --mode {pb_type,model}
                        Output file type, possible values are: pb_type and
                        model. Default value is pb_type

For example, to generate a pb_type xml file from adder.v, run

v2x -o adder.pb_type.xml adder.v

Or, to generate a model xml file, run

v2x --mode model -o adder.model.xml adder.v

v2x expects the module name to be the same as the file name. If it is different, make sure to specifiy it with the --top argument.

v2x --top BLOCK -o adder.pb_type.xml adder.v


The test cases are stored in tests/, and pytest can be used to run them.

rm -rf build  # run this step so that pytest uses the latest files for the tests
pytest -vv

If you are making changes to any python code, make sure that they follow the PEP8 style guide by running flake8.

flake8 tests
flake8 v2x


We use sphinx for our documentation and the files are stored in docs/. To host it locally (if you are planning to update it), you can use the Makefile inside.

First, run make env to prepare a Conda environment that contains the necessary packages to build and host the documentation site. After that, simply run make livehtml which starts a local server running at port 8000 with the documentation site.

cd docs
make env
make livehtml


VPR device models generation from Verilog with V2X - Karol Gugala - ORConf 2019

v2x orconf talk