Re: [libvirt] [PATCH] qemu: qxl devices don't support multifunction yet

On 09/29/2011 10:30 AM, Laine Stump wrote: > On 09/27/2011 05:13 AM, Daniel P. Berrange wrote: >> When we originally enabled multifunction for all PCI devices, we did so >> in the belief that this was effectively a no-op for guest OSes. ie it >> should not have changed guest OS behaviour at all, unless multiple >> devices >> were actually inserted in the slot. >> >> Evidentally this turns out to be incorrect. In other words we introduced >> a guest ABI change. This is very bad, because our stated goal is to have >> a stable guest ABI across libvirt& QEMU releases. >> >> Thus IMHO we need to disable *all* setting of the 'multifunction=on' >> parameter for all guests by default, to unbreak the ABI compatibility. >> >> Then we should introduce a new parameter 'multifunction='on' in the >> <address type=pci> element to allow it to be optionally enabled per >> device. > > > A couple of questions: > > 1) Is it possible/useful to have function > 0 without multifunction=on > in the qemu commandline? > > 2) If the answer to (1) is "No", if the XML has function > 0 but no > multifunction=on, should we implicitly add multifunction=on, or should > we log an error? Also: 3) if you explicitly/(implicitly?) set multifunction on for one function of a slot, does qemu automatically do so for other functions on the slot (ie, if you have a device that uses slot 1 function 1 (and turns on multifunction), then will slot 1 function 0 automatically have multifunction turned on too?)

-- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list