Considering that Windows has the concept of so-called ‘subsystems’ whereby you can run different systems side-by-side, starting with the POSIX subsystem and later the Windows Subsystem for Linux (WSL), it was probably only a matter of time before someone figured that the inverse was also completely reasonable. Rather than mucking about with Wine or such, we now got [Hailey Somerville]’s Linux Subsystem for Windows which is disappointingly called WSL9x rather than LSW.To make running Windows 9x inside Linux work, it was necessary to heavily patch a Linux kernel, as normally there are no provisions for such a subsystems unlike the NT kernel. Correspondingly, the Linux kernel is based on user-mode Linux and hacked to call Windows 9x kernel APIs instead of the POSIX ones.In order to use WSL9x you thus need to build said modified Linux kernel – currently at version 6.19 – along with a disk image containing an installed copy of Windows 9x. From there WSL9x can be loaded with the wsl command and you’re then free to cooperatively run the Win9x and Linux kernel side-by-side. This is reminiscent of Cooperative Linux (coLinux), which did pretty much the same except with Windows NT and Linux kernels running side-by-side. Maybe one day coLinux will be revived so that we can run 64-bit Windows alongside modern Linux?Thanks to [adistuder] for the tip.