[libvirt] Hypervisor raw options

Daniel P. Berrange berrange at redhat.com
Mon Mar 1 12:46:24 UTC 2010

On Fri, Feb 26, 2010 at 07:47:20PM +0100, Daniel Dehennin wrote:
> Hello,
> I wonder if it's possible to add hypervisor pass-through options, I add
> some usage of kvm -startdate and need to use a script which call kvm
> with the desired option.
> Something like:
> <emulator>/usr/bin/kvm</emulator>
> <emulator-options>
>     <option>-option1</option>
>     <option>-option2</option>
> </emulator-options>
> The several <option/> will be passed to the <emulator/> command.

The goal of the libvirt XML format is to provide a representation that is
consistent across all hypervisors, so that regardless of whether using
Xen, KVM, or VMWare an config parameter can be encoded that same way.

If we were to support your suggestion, every hypervisor in libvirt would
end up with a different XML configuration. In addition KVM / QEMU have
a history of renaming/breaking command line options, so there's no way of
guarenteeing that '-foo' from QEMU 0.9.1 still works with QEMU 0.10.0 or

If you have specific KVM arguments that libvirt does not yet support then
please either file a RFE bug report with details, or raise the issue on
this mailing list

WRT your example of -startdate, I posted patches for supporting that
last week


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