Actually most modern hypervisors allow nested virtualization.

https://www.linux-kvm.org/page/Nested_Guests

https://communities.vmware.com/docs/DOC-8970

Not even just modern hypervisors. The IBM mainframe hypervisor z/VM (and its predecessor VM/CMS) has supported nested virtualisation for decades. It was an important tool to support its own development (especially considering that mainframes were expensive and not even IBM could afford to give every mainframe OS developer a whole mainframe to themselves.)

Intel and AMD CPUs have supported hardware-accelerated nested virtualisation for quite some time now.

https://docs.microsoft.com/en-us/virtualization/hyper-v-on-w...

https://www.redhat.com/en/blog/inception-how-usable-are-nest...

Cygwin and Wine don't use virtualization. And even if they did, most hypervisors support nesting these days.

Because, of course, its not a emulator

Well, yes and no. On modern enough hardware you can do nested virtualisation, so you can run kvm in esxi on hyper-v if you want. Not that it's very usefull, but it is a fun weekend project nonetheless.

I use nested virtualization for Windows Desktop -> Linux VM -> minikube. Works great.

Obviously you could just run minikube under Windows, but then from the Linux VM you can't "minikube ssh" and whatnot, so nested virtualization makes everything a lot simpler.

You can even do nested virtualization without hardware support, it's just super duper slow and not a lot of hypervisors think it's worth the complexity increase.

Aside from all the other corrections, hardware virtualization support isn't necessary for virtualization.

WSL1 is not a "real" VM. https://blogs.msdn.microsoft.com/wsl/2016/05/23/pico-process...

Why? There's only one hypervisor involved for the initial "wine" environment.

Neither WINE nor WSLv1 use virtualisation. WSLv2 does use virtualisation however; but WINE still isn't a VM.

I was referring to WSLv2 here, so technically there is a hypervisor involved at the root level hosting the first WINE instance in the chain.

Further recursion WINE => Cygwin => WINE however will not require more nesting of hypervisors.