Re: USB Passthrough 1.1 performance problem...

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Dec 14, 2010 at 12:55:04PM +0100, Kenni Lund wrote:
> 2010/12/14 Erik Brakkee <erik@brakkee.org>:
> >> From: Kenni Lund <kenni@kelu.dk>
> >> 2010/12/14 Erik Brakkee <erik@brakkee.org>:
> >>>>
> >>>> From: Kenni Lund <kenni@kelu.dk>
> >>>>>
> >>>>> Does this mean I have a chance now that PCI passthrough of my WinTV
> >>>>> PVR-500
> >>>>> might work now?
> >>>>
> >>>> Passthrough of a PVR-500 has been working for a long time. I've been
> >>>> running with passthrough of a PVR-500 in my HTPC, since
> >>>> November/December 2009...so it should work with any recent kernel and
> >>>> any recent version of qemu-kvm you can find today - No patching
> >>>> needed. The only issue I had with the PVR-500 card, was when *I*
> >>>> didn't free up the shared interrupts...once I fixed that, it "just
> >>>> worked".
> >>>
> >>> How did you free up those shared interrupts then? I tried different slots
> >>> but always get conflicts with the USB irqs.
> >>
> >> I did an unbind of the conflicting device (eg. disabled it). I moved
> >> the PVR-500 card around in the different slots and once I got a
> >> conflict with the integrated sound card, I left the PVR-500 card in
> >> that slot (it's a headless machine, so no need for sound) and
> >> configured unbind of the sound card at boot time. On my old system I
> >> think it was conflicting with one of the USB controllers as well, but
> >> it didn't really matter, as I only lost a few of the ports on the back
> >> of the computer for that particular USB controller - I still had
> >> plenty of USB ports left and if I really needed more ports, I could
> >> just plug in an extra USB PCI card.
> >>
> >> My /etc/rc.local boot script looks like the following today:
> >> --
> >> #Remove HDA conflicting with ivtv1
> >> echo "0000:00:1b.0" > /sys/bus/pci/drivers/HDA\ Intel/unbind
> >>
> >> # ivtv0
> >> echo "4444 0016" > /sys/bus/pci/drivers/pci-stub/new_id
> >> echo "0000:04:08.0" > /sys/bus/pci/drivers/ivtv/unbind
> >> echo "0000:04:08.0" > /sys/bus/pci/drivers/pci-stub/bind
> >> echo "4444 0016" > /sys/bus/pci/drivers/pci-stub/remove_id
> >>
> >> # ivtv1
> >> echo "4444 0016" > /sys/bus/pci/drivers/pci-stub/new_id
> >> echo "0000:04:09.0" > /sys/bus/pci/drivers/ivtv/unbind
> >> echo "0000:04:09.0" > /sys/bus/pci/drivers/pci-stub/bind
> >> echo "4444 0016" > /sys/bus/pci/drivers/pci-stub/remove_id
> >
> > I did not try unbinding the usb device so I can also try that.
> >
> > I don'.t understand what is happening with the 4444 0016. I configured the
> > pci card in kvm and I believe kvm does the binding to pci-stub in recent
> > versions. Where is the 4444 0016%oming from?
> 
> Okay, qemu-kvm might do it today, I don't know - I haven't changed
> that script for the past year. But are you sure that it's not
> libvirt/virsh/virt-manager which does that for you?

If you use the managed="yes" attribute on the <hostdev> in libvirt
XML, then libvirt will automatically do the pcistub bind/unbind,
followed by a device reset at guest startup & the reverse at shutdown.
If you have conflicting devices on the bus though, libvirt won't
attempt to unbind them, unless you had also explicitly assigned all
those conflicting devices to the same guest.

Daniel