On Mon, Aug 09, 2010 at 08:34:23PM +0200, Daniel Veillard wrote: > On Mon, Aug 09, 2010 at 06:53:34PM +0100, Daniel P. Berrange wrote: > > On Mon, Aug 09, 2010 at 06:38:27PM +0200, Daniel Veillard wrote: > > > The balloon device is automatically added to qemu guests if supported, > > > but it may be useful to desactivate it. The simplest to not change the > > > existing behaviour is to allow > > > <memballoon type="none"/> > > > as an extra option to desactivate it (it is automatically added if the > > > memballoon construct is missing for the domain). > > > The following simple patch just adds the extra option and does not > > > change the default behaviour but avoid creating a balloon device if > > > type="none" is used. > > > > I really don't like the idea of 'type=none' devices in general. > > Since we automagically add the devices to describe an internal policy > I think we're at fault here. > > > I don't think we should have an element insides <devices> that > > doesn't actually represent a device. > > > > If we want to disable the balloon, then I think we should aim > > for an element or attribute elsewhere to toggle it. > > > > eg, perhaps the earlier <memory> element can indicate whether it > > supports ballooning. eg > > > > <memory ballonable='yes|no'>2423423432</memory> > > > > Thus if ballooning is not enabled, the <memballoon> device would > > never need to appear within <devices> > > Grumpf ... that mean at the internal stucture level we need to add an > extra field, that is detected at a completely different time in parsing > too ... more complex in general, but I can understand the purity POV. I don't see this as a real problem. It is no different from the way that we automatically add <controller> devices at the end of parsing, if we saw any <disk> or <channel> devices previously. Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list