[Libvir] Question about specifications of virsh start

Daniel P. Berrange berrange at redhat.com
Wed Nov 7 14:14:35 UTC 2007

On Wed, Nov 07, 2007 at 12:56:29PM +0900, Masayuki Sunou wrote:
> Hi
> I have a question about specifications of virsh start.
> It is necessary to remove "type=ioemu" from the configuration file of Xen,
> when HVM domain installed Para Virtualized Driver use unmodified driver
> on Xen 3.0.3.

Xen 3.0.3 is broken. Only Xen 3.1.0 works sanely wrt to PV drivers in HVM

If you leave off the 'type=ioemu' Xen 3.1.0 always sets up networking
so that both QEMU & PV drivers work.

> But,libvirt always adds "type=ioemu" to vif of HVM domain in xm_internal.c.
> Therefore virsh start cannot start correctly HVM domain installed
> Para Virtualized Driver.
> Could you teach why does libvirt disregard setting of configuration
> file and set type=ioemu ?

This whole rationale of changing the config file in order to setup PV
drivers is wrong.  The person in charge of admin for DomU will often
not have any access to Dom0 at all. So if the DomU admin wants to install
PV drivers, how can they change the config file ? Well they can't. Any
need to change the config file prior to install PV drivers is broken.
Hence why XenD was fixed in 3.1.0 to not be stupid.

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