On 05/04/2016 04:31 AM, Shivaprasad G Bhat wrote:
Further followup discussions in list on commit 192a53e concluded
that we should be leaving out the USB controller only for
i440fx machines as default USB can be used by someone on q35
at random slots.
The important reason this doesn't need to be suppressed for Q35 is that
usb controllers were supported prior to Q35 being supported (and the
"default" USB controller would never be added to a Q35 machine by
libvirt - if anything, it would automatically add a matching set of USB2
controllers.)