w/s/l? Microsoft closes 9-year-old feature request, open-sources Windows Subsystem for Linux WSL has also recently added official support for both Fedora and Arch distros. Andrew Cunningham – May 19, 2025 1:49 pm | 23 Credit: Microsoft Credit: Microsoft Story text Size Small Standard Large Width * Standard Wide Links Standard Orange * Subscribers only   Learn more Microsoft's Windows Subsystem for Linux has become an important tool for developers and power users since it was introduced in the Windows 10 Anniversary Update back in 2016, giving them access to a built-in Linux command line and Linux applications from within Windows. The company has steadily improved WSL since then, improving performance, making it easier to install and use, and adding features like GPU and audio support. But today as part of its Build developer conference, Microsoft announced that it would be making almost all of WSL open source, closing the very first issue that the then-new WSL project attracted on Github in 2016. "WSL could never have been what it is today without its community," writes Microsoft Senior Software Engineer Pierre Boulay in the company's blog post. "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." 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); and the p9rdr.sys and p9np.dll files that handle filesystem redirection from Windows to Linux (in other words, making it so that Windows can easily access the Linux filesystem). Microsoft didn't close the door to open-sourcing those components but also didn't say if or when it planned to make them open source. Though WSL uses some of the same technologies as virtual machines, WSL's speed, low resource usage, and integration with Windows makes it much more seamless to install and use than traditional virtual machines that maintain more separation between the host and guest operating system. Around the release of Windows 11 in 2021, Microsoft made WSL something that was installed and updated via the Microsoft Store rather than something built into the operating system, making it easier to add new features without requiring the potential disruption of a full Windows update (and also possibly making it easier to open source the code without posting source code for other parts of Windows). This isn't the only major improvement Microsoft has helped to release for WSL recently. Earlier this month, the company announced that Fedora is now an officially supported WSL distribution, joining Ubuntu (still the default) and a number of other distributions. Arch Linux also became an officially supported distribution back in April; both Fedora and Arch are taking advantage of changes Microsoft announced last year to make it easier to build new WSL distributions. Windows users can install WSL by choosing a distribution from the Microsoft Store or by opening a command-line window and typing wsl --install. Users can install multiple distributions at once and switch between them based on what they're running or testing; typing wsl --list --online at the command line will also show you all of the distributions that Microsoft officially supports if you don't want to use Ubuntu. Andrew Cunningham Senior Technology Reporter Andrew Cunningham Senior Technology Reporter Andrew is a Senior Technology Reporter at Ars Technica, with a focus on consumer tech including computer hardware and in-depth reviews of operating systems like Windows and macOS. Andrew lives in Philadelphia and co-hosts a weekly book podcast called Overdue. 23 Comments