Re: IMPORTANT - : Need help on USB port virtualization with Xen hypervisor

[Jürgen Groß <jgross@xxxxxxxx>]

On 16.03.24 00:32, Stefano Stabellini wrote:
> Hi Dominique,
>
> You posted this configuration:
>
> device_model_args = [ "
>                        "-device","nec-usb-xhci,id=xhci",
>                        "-device","usb-host,bus=xhci.0,hostbus=1,hostport=13",
>                        "-device","usb-host,bus=xhci.0,hostbus=1,hostport=10",
>                        "-device","usb-host,bus=xhci.0,hostbus=1,hostport=2",
>                        "-device","usb-host,bus=xhci.0,hostbus=2,hostport=2",
>                        "-device","usb-host,bus=xhci.0,hostbus=2,hostport=1",
>                        "-device","usb-host,bus=xhci.0,hostbus=1,hostport=1"]
>
> It looks like you are using QEMU-based USB passthrough. Basically QEMU
> (independently from Xen) is accessing the USB device in Dom0 and
> exposing a corresponding device to the guest. I am not sure if there is
> anything that can be done in QEMU to support USB 3.0 with high speed,
> people in CC might know.
>
> There two other alternatives to this approach. You can use PV USB
> Passthrough instead. Juergen (CCed) is the original author. I am not
> sure if that supports USB 3.0 either.
PV USB doesn't support USB 3.0.

Instead of using device_model_args= in the guest configuration I'd rather
use the usbctrl= and usbdev= items (see the related xl.cfg(5) man page).
I'm not sure this will really make a performance difference, though.


Juergen