Re: [Xen-users] [XEN 3.3 - PCI passthrough] - interaction latencies with /dev/ttyUSB0

[Ken Cobler <kcobler@xxxxxxxxxxxxxx>]

jer jer wrote:
> Thanks for your help Ken,
>
> I'm gonna have a look to the USB over IP solution.
> Nevertheless, in addition to my post, I ran further tests and noticed 
> that when processing test on dom0 (no passthrough),  everything works 
> fine (no more latencies).
> So, I'm about to conclude that the problem is due to PCI passthrough.
> I'm a litlle bit surprised, cause I thought that doing this would have 
> given direct USB access.
> Is it known that pci passthrough pull down performances?
>
> Furthertmore, I've read that XEN 3.4 will introduce virtualized USB 
> driver. So can we concluide that no more support will be done on PCI 
> passthrough?
> Finally, do you have any perf issues running USB over IP?
>
> Tks a lot!
It would be great to see complete USB virtualization in Xen. 

However, I don't think that would take away from PCI passthrough.  
Simply, there are other devices that are PCI devices and not USB, that 
could be passed to a domU.

With regards to USB over IP, I have only implemented a Digiboard 
hardware product called AnywhereUSB, 
http://www.digi.com/products/usb/anywhereusb.jsp
The only concern someone may have about AnywhereUSB is it will only 
support USB 1.0 speeds for all devices.  In my application, that was not 
an issue.

Ken Cobler

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