Virtual Box is still the easiest to use VM software for Linux and that sucks.
libvirt has being a pain in the ass to learn and some of the tooling straight up doesn't work (at least on my system). I've also yet to get proper mouse support working or clipboard sharing.
qemu-img convert -f vdi -O qcow2 YourVirtualBoxVM.vdi YourQEMUVM.qcow2
For me it was a windows VM, because… school shitty stuff on windows. And I use that command for launching the VM.
qemu-system-x86_64 -enable-kvm -cpu host -drive file=Windows10Home64Bit.qcow2 -m 3G -net nic -net vde -hda
I have problems with the network if I don’t add the -net nic -net vde -hda options, and even with that my VM network is limitied at 10% of my linux host network.
Networking with QEMU is the only hard thing.
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