Re: [Xen-users] usb passthrough

[Chris <tknchris@xxxxxxxxx>]

I wonder why it's limited to 1.1 i would imagine that is a hard coded  
limit but given a faster system shouldn't the emulation be faster? Who  
could shed more light on why?
Sent from my iPhone

On Feb 26, 2010, at 5:44 PM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:

> On Fri, Feb 26, 2010 at 05:34:14PM -0500, chris wrote:
> > I would be curious to see benchmarks comparing usb device passthrough
> > with vt-d passthrough of a usb controller + device. Would be
> > interesting to see what differences if any there are. If I get some
> > time I will try to test this.
> See here for benchmark results:
> http://www.xen.org/files/xensummit_intel09/PVUSBStatusUpdate.pdf
>
> pvusb performance seems to be pretty close to dom0 native usb  
> performance.
> If using the normal qemu-dm usb passthrough it is limited to  
> emulated usb 1.1,
> so that'll be slow.
>
> -- Pasi
>
> > - chris
> >
> > On Fri, Feb 26, 2010 at 5:00 PM, James Harper
> > <james.harper@xxxxxxxxxxxxxxxx> wrote:
> > > Pvusb should work for most things. You might be thinking of the  
> > > USB frontend
> > > in gplpv which only works with a very limited number of storage  
> > > devices (and
> > > probably not at all since the last update)
> > >
> > > James
> > >
> > > Sent from my iPhone
> > >
> > > On 27/02/2010, at 5:25, "chris" <tknchris@xxxxxxxxx> wrote:
> > >
> > > > Pasi,
> > > >
> > > > I know, my understanding was that pvusb was simply for exposing usb
> > > > mass storage as a block device to the domain. I've never actually  
> > > > used
> > > > it but I believe you can do this with a hvm domain without anything
> > > > special. If anyone can actually confirm this it would be good to  
> > > > know
> > > > :)
> > > >
> > > > As far as his original question, he needs vt-d to passthrough any
> > > > physical device to a hvm domain.
> > > >
> > > > - chris
> > > >
> > > > On Fri, Feb 26, 2010 at 10:03 AM, Pasi Kärkkäinen <pasik@xxxxx 
> > > > i> wrote:
> > > > > On Fri, Feb 26, 2010 at 10:00:34AM -0500, chris wrote:
> > > > > > He said it was a HVM guest. I don't think you can passthrough  
> > > > > > to a hvm
> > > > > > domain anything except usb storage with pvusb, correct?
> > > > > pvusb is different from the 'normal' usb=1 / usbdevice = []  
> > > > > stuff..
> > > > > I'm not totally sure what devices are supported with pvusb and  
> > > > > with the
> > > > > normal usb passthrough.
> > > > >
> > > > > -- Pasi
> > > > >
> > > > > > On Fri, Feb 26, 2010 at 9:49 AM, Pasi Kärkkäinen <pasik@ik 
> > > > > > i.fi> wrote:
> > > > > > > On Fri, Feb 26, 2010 at 09:49:38AM -0300, Sergio Charpinel Jr.  
> > > > > > > wrote:
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > I want to use a webcam in a HVM guest, but my dom0 doesnt  
> > > > > > > > support VT-d
> > > > > > > > (just VT).
> > > > > > > USB passthrough doesn't require VT-d, it's only required for  
> > > > > > > PCI device
> > > > > > > passthrough to HVM guests.
> > > > > > >
> > > > > > > > I tried passing the parameters usb=1 and usbdevice = [ '..' ]  
> > > > > > > > and I
> > > > > > > > could see an usb device in domU. But it does not know which  
> > > > > > > > device is.
> > > > > > > > Which are the possibilites to do that? I prefer to use hvm  
> > > > > > > > machines,
> > > > > > > > but if it is not possible, with PV machines it can work?
> > > > > > > With PV guest you could passthrough the whole USB controller  
> > > > > > > (the PCI
> > > > > > > device)..
> > > > > > >
> > > > > > > -- Pasi
> > > > > > >
> > > > > > >
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