The Windows Subsystem for Linux is now open source

Original Article ↗ Hacker News Discussion ↗

Motivation, Layoffs & Strategy

  • Some speculate the timing is linked to recent layoffs despite record earnings; others note both layoffs and open-sourcing are multi‑year decisions, so the causal link is unclear.
  • Several comments argue Microsoft open-sources primarily for strategic benefit: to grow cloud/platform usage, shift maintenance to the community, and keep developers on Windows rather than losing them to Linux.
  • A minority see this as “embrace, extend, extinguish” theater; others counter that even self‑interested open‑sourcing is far better than the old closed‑Microsoft era.

What’s Actually Open-Sourced

  • The user‑space WSL code and Plan9-based filesystem components are now under the MIT license.
  • The key WSL1 kernel driver (lxcore.sys) is not included, which disappoints people who still use WSL1 for its syscall translation model.
  • Some worry this might foreshadow reduced internal investment; others think it’s just an openness/PR move.

Kernel, Vanilla Linux & Technical Details

  • WSL2 runs a full Linux kernel under Hyper‑V; patches are largely upstreamed, with remaining bits mainly for graphics (dxgkrnl), clock sync, CUDA/WSLg.
  • Using a “vanilla” kernel is already possible but may lose GPU/WSLg integration; open code should make BSD or other backends more realistic for tinkerers.
  • Kernel version lag is a recurring complaint (e.g., WSL2 on 6.6 vs distros targeting 6.12+).

WSL vs Native Linux: Experience & Trade‑offs

  • Enthusiasts say WSL gives “the best of both worlds”: Windows apps (Office, CAD, games) plus a real Linux dev environment, with excellent VS Code/JetBrains integration and easy multi‑distro setups.
  • Others argue that for Linux‑centric work it’s strictly worse than native Linux (VM overhead, integration bugs, mental overhead of two OSes).
  • WSL1 still has fans for faster access to Windows files and simpler networking; WSL2 is preferred for correctness and container compatibility.

Performance, Filesystems & Networking

  • Major pain point: file I/O on Windows files from WSL2 via 9P (e.g., git status, find on large trees) can be orders of magnitude slower than native or WSL1, even with “dev drives”.
  • Some attribute slowness to NTFS, others to Windows I/O filters (Defender, etc.) plus the network-like 9P path. Workarounds: keep code on the WSL VHD, disable AV, or avoid cross‑boundary work.
  • Networking issues crop up around VPNs, corporate stacks, sleep/wake, and mDNS; experiences vary from “rock solid” to “daily breakage”.
  • systemd under WSL2 is reported as slow to start and can delay shell startup; many disable it.

Windows Frustrations & Privacy Concerns

  • Many comments express strong dislike of Windows 10/11: intrusive telemetry, UI ads (Start, lock screen, widgets), forced or nagging updates, Microsoft account pressure, and “Copilot as spyware”.
  • Some use Enterprise/LTSC builds, group policy, or custom install media to strip most of this, but others see the need to do so as itself unacceptable.
  • For some, WSL is “great tech in a hostile OS”; for others, it’s the only reason they tolerate Windows at all.

Alternatives & Comparisons

  • On Linux, people point to Distrobox, toolbox, LXC/incus, systemd‑nspawn, and plain VMs (KVM/QEMU, GNOME Boxes) as equivalents for multi‑distro development without a second kernel.
  • Linux host + Windows VM with GPU passthrough is favored by some for gaming, CAD, and legacy tools; others find GPU passthrough and DRM too painful and stick with Windows host + WSL.
  • Wine/Proton are praised as increasingly capable (especially for games) but still unreliable for many commercial productivity apps (Adobe, MS Office, niche engineering tools).
  • macOS gets mixed reviews: great hardware, decent dev UX, but limited third‑party/pro gaming support and ARM/x86 virtualization complications; Asahi is admired but seen as heavy reverse‑engineering with little Apple help.

Security & Enterprise Angle

  • Security people worry WSL creates a “blind spot”: a Linux VM on corporate Windows endpoints that EDR/agents don’t fully see or control.
  • Others note WSL has had real data‑loss bugs (e.g., VHD corruption, disk‑space reclaim issues) and that losing a WSL distro can be catastrophic for un‑backed‑up dev data.

Naming & Architecture Confusion

  • Many are still confused by “Windows Subsystem for Linux”, arguing “Linux subsystem for Windows” would better reflect the reality.
  • Others clarify that “subsystem” is an NT architectural term (Win32, POSIX, OS/2), so this is the Windows subsystem that runs Linux processes, even though WSL2 is now primarily a specialized Hyper‑V VM with deep integration.