> I called it a distant relative of the NT POSIX environment and some senior MS bod disagreed and – when I said [[citation needed]] – eventually linked to a bun

> I called it a distant relative of the NT POSIX environment and some senior MS bod disagreed and – when I said [[citation needed]] – eventually linked to a bunch of videos and stuff that say that WSL1 is a whole new translation layer and not a kernel personality at all. As far as I understand it, WSL1 was a complete reimplementation and did not use any code from the old POSIX subsystem/SUA/Interix. In particular, SUA had a number of long-standing limitations (like when replacing open files) which were probably unfixable without rewriting everything anyway. It allegedly is a continuation of Project Astoria which implemented only the minimum necessary part to make Android apps run, but was refocused to run all Linux applications.