WSL1 was "Linux API on top of Windows", WSL2 is "Linux VM on top of Windows"

More like,

WSL1 was "Linux API on top of NT kernel picoprocesses", WSL2 is "Linux VM on top of Hyper-V"

I wish WSL1 was open sourced

Picoprocesses are based on Drawbridge research, so at least there is some reading about how it all works,

https://www.microsoft.com/en-us/research/project/drawbridge/

https://learn.microsoft.com/en-us/archive/blogs/wsl/windows-...

https://www.zdnet.com/article/under-the-hood-of-microsofts-w...

That’s more like WSL1, yes.

WSL2 is no longer a VM, afaik.

Other way around (1 wasn't, 2 runs in a managed HyperV VM) https://learn.microsoft.com/en-us/windows/wsl/compare-versio...