* QEMU calls itself an emulator because emulation was its original intent; that it was possible to relatively easily modify it to use hardware virtualization rather than emulating the CPU was a happy accident some time later
* for the CPU the "virtualization"/"emulation" distinction is huge -- if you can use the CPU's hardware assist to directly run guest code things will be fast; if you're emulating the guest CPU things will be very much slower
* the process being run isn't "kvm-qemu" unless your distro
is providing back-compatibility wrappers (which in turn are only there because the changes to QEMU to make it work with KVM were for some years maintained out of tree)
* KVM is absolutely a hypervisor; libvirt is not, it is a management layer that can configure and control a hypervisor
* you can't use Xen with KVM, because they're both hypervisors
mpyne
Bingo. In fact I remember using QEMU briefly some years before virtualization or "VMWare" was even a widely-known term, and that was only because of my interest in the emulation scene at the time.
kijiki
KVM supports nested virtualization, so you can run Xen inside a KVM VM. VMware does as well.
Xen paravirt has always run inside VMs, even before nesting support. I used to run it in VMware all the time for development purposes.
* QEMU calls itself an emulator because emulation was its original intent; that it was possible to relatively easily modify it to use hardware virtualization rather than emulating the CPU was a happy accident some time later
* for the CPU the "virtualization"/"emulation" distinction is huge -- if you can use the CPU's hardware assist to directly run guest code things will be fast; if you're emulating the guest CPU things will be very much slower
* the process being run isn't "kvm-qemu" unless your distro is providing back-compatibility wrappers (which in turn are only there because the changes to QEMU to make it work with KVM were for some years maintained out of tree)
* KVM is absolutely a hypervisor; libvirt is not, it is a management layer that can configure and control a hypervisor
* you can't use Xen with KVM, because they're both hypervisors