Microsoft is making its Windows Subsystem for Linux (WSL) open-source today, opening up the code for community members to contribute to. After launching WSL for Windows 10 nearly nine years ago ...

HJBC/Getty Images It took Microsoft long enough, but the company has finally open-sourced its Windows Subsystem for Linux (WSL) code. The announcement was made at the Build 2025 developer ...

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It didn’t, however, make Lxcore.sys, P9rdr.sys, or p9np.dll open source, as they are part of Windows. If you want to download the source code for version 2.5.7, GitHub is the place to go.

Only two elements of WSL remain closed-source for now: an lxcore.sys kernel driver used for WSL 1 (the initial version of WSL that is still supported, though new installs default to 2019's WSL 2 ...

This state made the open-source shift, and chances are it won't be the last. Written by Steven Vaughan-Nichols, Senior Contributing Editor June 16, 2025 at 1:49 a.m. PT querbeet/Getty Images ...

My colleague Paul Barker did an excellent article on this in itworldcanada.com and in Channel Daily News (where he’s the editor) entitled Red Hat turns the world of open source Linux upside down.

The other component that will remain closed source are the P9rdr.sys and p9np.dll files that make it possible to use “\wsl.localhost” for filesystem redirection from Windows to Linux.