Development setup

This section is a complement to the Advanced installation guide section, with the goal of setting up a development environment and a development version of the package.

For convenience, we suggest creating a virtual environment as a way to isolate your development environment:

$ python3 -m venv aihwkit_env
$ cd aihwkit_env
$ source bin/activate
(aihwkit_env) $

Downloading the source

The first step is downloading the source of the library:

(aihwkit_env) $ git clone
(aihwkit_env) $ cd aihwkit


The following sections assume that the command line examples are executed in the activated aihwkit_env environment, and from the folder where the sources have been cloned.

Compiling the library for development

After installing the requirements listed in the Advanced installation guide section, the shared library can be compiled using the following convenience command:

$ python build_ext --inplace

This will produce a shared library under the src/aihwkit/simulator directory, without installing the package.

As an alternative, you can use cmake directly for finer control over the compilation and for easier debugging potential issues:

$ mkdir build
$ cd build
build$ cmake ..
build$ make

Note that the build system uses a temporary _skbuild folder for caching some steps of the compilation. While this is useful when making changes to the source code, in some cases environment changes (such as installing a new version of the dependencies, or switching the compiler) are not picked up correctly and the output of the compilation can be different than expected if the folder is present.

If the compilation was not successful, it is recommended to manually remove the folder and re-run the compilation in a clean state via:

$ make clean

Using the compiled version of the library

Once the library is compiled, the shared library will be created under the src/aihwkit/simulator directory. By default, this folder is not in the path that Python uses for finding modules: it needs to be added to the PYTHONPATH accordingly by either:

  1. Updating the environment variable for the session:

    $ export PYTHONPATH=src/
  2. Prepending PYTHONPATH=src/ to the commands where the library needs to be found:

    $ PYTHONPATH=src/ python examples/


Please be aware that, if the PYTHONPATH is not modified and there is a version of aihkwit installed via pip, by default Python will use the installed version, as opposed to the custom-compiled version. It is recommended to remove the pip-installed version via:

$ pip uninstall aihwkit

when developing the library, in order to minimize the risk of confusion.

Compilation flags

There are several cmake options that can be used for customizing the compilation process:





Build with CUDA support



Build the C++ test binaries



BLAS backend of choice (OpenBLAS or MKL)



Use fast mod



Use fastrand



Target CUDA architectures


The options can be passed both to setuptools or to cmake directly. For example, for compiling and installing with CUDA support:

$ python build_ext --inplace -DUSE_CUDA=ON -DRPU_CUDA_ARCHITECTURES="60;70"

or if using cmake directly:

build$ cmake -DUSE_CUDA=ON -DRPU_CUDA_ARCHITECTURES="60;70" ..

Passing other cmake flags

In the same way flags specific to this project can be passed to, other generic cmake flags can be passed as well. For example, for setting the compiler to clang in osx systems:

$ python build_ext --inplace -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_COMPILER=/usr/bin/clang++

Environment variables

The following environment variables are taken into account during the build process:

Environment variable



If present, sets the PyTorch dependency version in the built Python package