Linux: Microsoft Wsl’s Decade-long Journey To Open Source

LONDON — Craig Loewen, Microsoft’s elder merchandise head successful complaint of Windows Subsystem for Linux (WSL), and Clint Rutkas, main merchandise head lead who oversees WSL, at Canonical‘s Ubuntu 25.10 Summit told nan communicative for nan first clip of really WSL was yet unfastened sourced. It was a long, unusual trip.

The Origins of WSL successful Project Astoria

You see, WSL’s communicative began backmost successful 2010 pinch Project Astoria, aka Windows Bridge for Android. This stillborn task was intended to alteration group to tally Android apps connected Windows Phone via a translator furniture successful nan Windows 10 Mobile kernel. Since you’re improbable to person a moving Windows Phone successful your pocket, you cognize really that turned out.

The first prototype translated Linux strategy calls into Windows NT kernel calls, laying nan groundwork for nan 2016 motorboat of Bash and Ubuntu connected Windows. This first effort, which Canonical helped build, recompiled Cygwin’s unfastened root utilities to tally natively connected Windows. Dustin Kirkland, past a personnel of Canonical’s Ubuntu Product and Strategy team, explained, “We’re talking astir bit-for-bit, checksum-for-checksum Ubuntu ELF binaries moving straight successful Windows.”

The First Iteration: The WSL 1.0 Compatibility Layer

At nan time, Kirkland said, “A squad of crisp developers astatine Microsoft [had] been difficult astatine activity adapting immoderate Microsoft Research exertion to fundamentally execute existent clip translator of Linux syscalls into Windows OS syscalls. Linux geeks tin deliberation of it arsenic benignant of nan inverse of WINE, [the unfastened root programme that enables group to tally Windows programs connected Linux] — Ubuntu binaries moving natively successful Windows.”

This was nan predecessor of WSL 1.0. This was a compatibility furniture that enabled group to tally Linux distributions, specified arsenic Ubuntu, openSUSE and Fedora, by translating Linux strategy calls into Windows NT kernel calls, utilizing a system called “pico processes.” It was released successful 2017 arsenic portion of nan Windows 10 Fall Creators Update.

A New Approach: The Rise of WSL 2 and its Popularity

Users, who were chiefly developers, liked it, but they each reported that WSL 1.0 was slow. So, Microsoft backed off, looked it complete and tried a caller measurement to tally Linux and its applications. The squad decided to develop their ain Linux kernel. Thus, WSL 2 took a fundamentally different approach. Instead of emulation, WSL 2 uses a lightweight managed virtual instrumentality (VM) to tally nan Microsoft Linux kernel, which is updated via Windows Update.

This type became highly celebrated among developers, peculiarly aft its unchangeable merchandise successful May 2020. Millions of users adopted it for programming, strategy management and unreality engineering workflows. Its fame accelerated betwixt 2021 and 2023, pinch nan percent of developers utilizing WSL arsenic their superior operating strategy increasing astir fivefold successful a azygous year, from 3% to complete 14% according to nan Stack Overflow Developer Survey of 2022.

The Internal Push to Open Source WSL astatine Microsoft

Within Microsoft, WSL’s developers began to push to unfastened root WSL 2.0. As Loewen said, it only made sense. After all, “Linux is unfastened source, right? And we are moving connected a Linux merchandise that brings Linux to nan Windows operating system. We want it to beryllium integrated pinch what nan organization is and beryllium wherever nan organization is. It makes consciousness we’re there. And truthful that’s business value, embracing nan community.”

Loewen added, “It couldn’t person happened immoderate earlier “because WSL was initially truthful tightly coupled to nan Windows kernel that we couldn’t unfastened root it. Even if we wanted to, we wouldn’t beryllium allowed to. And past complete time, we started doing it, because we were like, ‘This needs to beryllium unfastened source!’ So we started removing each of nan backstage calls, decoupling everything, and that’s what fto america get to wherever we are.”

Overcoming Challenges to Decouple WSL from Windows

This took a agelong time. Loewen said, “Years were spent decoupling backstage APIs and refactoring long-standing dependencies, allowing Microsoft to yet people nan afloat codification responsible for WSL.”

The push to unfastened root WSL internally successful Microsoft progressive 3 main strategies: celebrating organization involvement, demonstrating business worth and thoroughly evaluating some benefits and costs. Internally, nan squad based on that unfastened sourcing WSL dovetailed pinch Microsoft’s broader strategy of supporting developer instrumentality users. Linux, being unfastened root by nature, requires a community-centric attack for personification spot and effective improvement successful nan Windows environment.

It was a difficult slog astatine times. Rutkas acknowledged that “open sourcing is rewarding, but it takes clip and effort. You must person your stakeholders.”

The Immediate Success of an Open Source WSL

Once done, though, it was a smashing success. Rutkas said, “As soon arsenic we unfastened sourced, it went from 15,000 stars to 30,000 positive stars connected GitHub. So that was bully — and that was successful 1 day. It skyrocketed. It was connected Hacker News, wherever it was nan number 1 station for, I think, 24 hours, which is unheard of. So, we knew we made nan correct move.”

This modulation reinforced that not each technologies request to beryllium proprietary. Yes, moreover successful Microsoft. WSL’s existent value, nan brace said, was enabling developer productivity, not “secret sauce” differentiation. The squad said it was impervious that unfastened root tin thrust ngo worth that outweighs competitory concerns. By embracing nan unfastened root model, Microsoft empowered outer developers to unlock solutions and improvements astatine a gait backstage teams could not match.

A Blueprint for Future Open Source Projects astatine Microsoft

The WSL team’s unfastened root efforts now guideline champion practices astatine Microsoft. It’s been nan blueprint for different awesome Microsoft programmer-oriented projects specified arsenic Windows Terminal, PowerToys and Microsoft’s caller CLI editor, Edit. The consequence of prioritizing unfastened source-first, nan brace say, has proven to beryllium measurable, affirmative and a blueprint for early unfastened root translator astatine Microsoft.

Microsoft an unfastened root package leader? Who would person thought moreover a decade ago?

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