local-dev.md

Local development of kernels

Introduction

kernel-builder builds kernels in a sandbox. This has various benefits, such as building kernels for a wide range of Torch versions, compatibility with older C library versions and avoiding accidental dependencies.

However, this is not ideal during kernel development, since language servers and IDEs do not interpret the build.toml file. As a result, code completion will typically not work. kernel-builder provides the build2cmake utility to generate CMake files to build native code and setuptools files for building the kernel as a regular Python package. Since CMake and setuptools are widely supported by IDEs, this provides a much-improved development experience.

Installing build2cmake

build2cmake is available as a Rust crate. After installing Rust, it can be built and installed as follows:

$ cargo install build2cmake

Generating a Python project with build2cmake

build2cmake generates a CMake/Python project from a build.toml file. The invocation is as follows:

$ build2cmake generate-torch build.toml -f

The -f flag is optional and instructs build2cmake to overwrite existing files.

It is recommended to do an editable install of the generated project into your Python virtual environment for development:

$ pip install wheel # Needed once to enable bdist_wheel.
$ pip install --no-build-isolation -e .

Warnings:

• Kernels built in this way should not be published on the Kernel Hub. They do not fulfill the kernel requirements.
• Do not add the generated files to Git. build2cmake has regular updates and you generally want to use files generated by the latest version.