After 9 Years, Microsoft Fulfills This Windows Feature Request

Most of the source code for the Windows Subsystem for Linux (WSL) has now been released on GitHub. Microsoft announced on May 19 that developers and hobbyists can now build WSL from source, explore the code, experiment with modifications, and contribute directly to its development.

What is Windows Subsystem for Linux?

Windows Subsystem for Linux is a feature that allows users to run a Linux environment inside a Windows machine without requiring a virtual machine or dual boot setup. The first version, WSL, was released in 2016. Shortly after its launch, the first issue raised about WSL on GitHub questioned whether the feature would ever be open sourced; nearly a decade later, Microsoft has answered that request.

WSL is made up of components that bridge Windows and the WSL 2 (which was released in 2019) virtual machine. WSL 2 itself launches the virtual machine, starts distributions, mounts file access shares, and enables additional functionality. Linux files are shared with Windows via a plan9 server implementation.

Some components included in the Windows image have not been open-sourced code:

• Lxcore.sys, the kernel-side driver that powers WSL 1.
• P9rdr.sys.
• P9np.dll, both of which run the “\\wsl.localhost” filesystem redirection from Windows to Linux.

How to Contribute to WSL

“We’ve seen how much the community has contributed to WSL without access to the source code, and we can’t wait to see how WSL will evolve now that the community can make direct code contributions to the project,” wrote Microsoft Senior Software Engineer Pierre Boulay in a blog post.

The WSL code is available on GitHub. Microsoft continues to collaborate closely with the WSL community to identify bugs and gather feature suggestions.