sunrat wrote: ↑2021-10-17 12:20
you don't understand the capabilities of KVM/QEMU
Common problem. The two solutions are not in the same league really. Vbox has proven not to be as stable long term, that is across release upgrades, and with migration of the host computer.
The XP(pro) vm I'm watching live TV on right now was installed July 10, 2018. Another XP (home) was installed Feb 13, 2017. They were crafted on Jessie, on a X8D supermicro. Now running on a X9S running Stretch, old. But they have also run on X9D under Buster, same images. That is a long term durability I don't believe is so easy with Virtual Box. They will run on Bullseye, as of yet they don't *need* to. I don't like doing things more than once.
Another feature of VMM is the ability to network the nest. That Stretch VMM reaches into Buster/Bullseye qemu servers remotely. So virtual machines can be utilized by any VMM equiped desktop, with or without kvm/qemu capability. The qemu server does need VMM. This segmentation of function is not available with Virtual Box.
Next is the reality that VirtualBox is a laptop program! It is useful for hardware limited local use. On a 'real computer', whatever we call full sized computers now - 'towers' 'racks' or the ambiguous 'desktop', the extra PCIe slots useful with vfio hardware pass. That's not so easy with VirtualBox, and where the dividing line is very clear. KVM/QEMU is paravirtualize capable, that's hardware assisted and works much better than 'addon extensions'. Btw, I prefer 'desktop' chassis.
Qemu is substantially lighter once the use case is beyond ONE vm. I used the term 'nest', a config far beyond a laptop. I can test on multiple monitors with multiple gpu's without getting out of my chair, that config is a moving target...Not only can I do many things at once, other people can join in!
So be fair, VBox and qemu/kvm are not the same thing. VMWare is another story, and basically the target for qemu/kvm/vmm. It would be nice if more noobs and converts wanted to improve the open source solutions. The incomplete solutions already in progress for everything mentioned could be finished with more audience.