Comment 3 for bug 1846392

Ahh, yeah, the FAQ ...! :D A lot of work testing stuff and then I forgot about that. (I _did_ have a look into it when I wondered about the binaries whose name ends with a W.)

Anyways, WHPX is not available for Win8.1, but only starting with Win10 _1803_, they say:
https://docs.microsoft.com/en-us/xamarin/android/get-started/installation/android-emulator/hardware-acceleration?pivots=windows#accelerating-with-hyper-v

And indeed, '.\qemu-system-x86_64.exe -accel whpx' will return
...\qemu-system-x86_64.exe: Could not load library WinHvPlatform.dll.
...\qemu-system-x86_64.exe: failed to initialize WHPX: Function not implemented

Fortunately enough I do have Win10 1803 in dual-boot on this machine. Let's see how it goes!*

*[At this point, I could have saved this message, switched OS and tried it, such that I could write about the outcome here, but that wouldn't really belong to this bug, so instead, I'll send this first and then I'll maybe file a fresh bug if WHPX doesn't work either. ;) ]