Microsoft Has WSL, But This Developer Built One for Windows 95

Linux has had a quiet takeover of computing. It powers all of the world’s top 500 supercomputers and Android, which runs on billions of smartphones.

It has also found its way into places that have nothing to do with traditional computing. Smart TVs run some variant of it. Cars run it. If something has a processor and a purpose, there is a good chance Linux is involved somewhere.

Over the years, we have also seen some interesting experiments involving Linux and Windows together. loss32 runs an entire desktop as Win32 software under Wine, and Microsoft’s WSL has made Linux a part of Windows 10 and beyond.

Now, Hailey, an open source developer, has taken that idea and turned it around. Instead of Linux hosting Windows apps, she has made Windows 9x host Linux.

WSL9x: Overview ⭐

The project brings a Linux subsystem to Windows 9x, covering 95, 98, and ME, with Linux kernel 6.19 running alongside the Windows 9x kernel, letting both operate on the same machine at the same time.

As for how it works, a patched kernel from Hailey’s win9x-um-6.19 branch sits at the core, which is compiled using the User Mode Linux architecture and loaded at a fixed base address of 0xd0000000.

A VxD (virtual device driver) handles initialization, loads the kernel off disk and manages the event loop for page faults and syscalls. Since Win9x lacks the right interrupt table support for the standard Linux syscall interrupt, WSL9x reroutes those calls…