Re: kvm binary names

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Mar 30, 2009 at 05:12:30PM -0400, Bill Davidsen wrote:
> Daniel P. Berrange wrote:
> >On Fri, Mar 20, 2009 at 10:57:50AM -0700, jd wrote:
> >>Hi
> >>   What is the motivation for having different kvm binary names on 
> >>   various linux distributions.. ? 
> >>-- kvm
> >>-- qemu-system-x86_84
> >>-- qemu-kvm
> >
> >I can tell you the history from the Fedora POV at least...
> >
> >We already had 'qemu', 'qemu-system-x86_64', etc from the existing
> >plain qemu emulator RPMs we distributed.
> >
> >The KVM makefile creates a binary call qemu-system-x86_64 but this
> >clashes with the existing QEMU RPM, so we had to rename it somehow
> >to allow parallel installation of KVM and QEMU RPMs.
> >
> >KVM already ships with a python script called 'kvm' and we didn't
> >want to clash with that either, so we eventually settled on calling
> >it 'qemu-kvm'. Other distros didn't worry about clash with the python
> >script so called their binary just 'kvm'
> >
> Don't stop there, why does Fedora have both "qemu-ppc" and 
> "qemu-system-ppc" and so forth? There are many of these, "arm" and "m68k" 
> for instance. On x86 I assume that they are both emulated, and they are not 
> two names for the same executable or such, so what are they and how to 
> choose which to use?

Those are totally different things.  qemu-$ARCH  is a userspace
emulator, while qemu-system-$ARCH is a full machine emulator. 

The userspace emulator lets you directly execute binaries from the
other non-native arch. The machine emulator provides a complete
virtual machine where you can rnu an entire OS.


Daniel
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