Re: [Qemu-devel] USB passthrough in qemu

[Gerd Hoffmann <kraxel@redhat.com>]

On Do, 2014-06-12 at 10:53 +0200, Michal Suchanek wrote:
> Hello,
> 
> I hit bug https://bugs.launchpad.net/qemu/+bug/685096 and found the
> usb2.txt file in the source which is sadly not installed by the
> distribution.
> 
> What I would like is an -usb2 option which instantiates both uhci/ohci
> and ehci root hubs. I don't particularly care if the buses appear as
> companion or separate.

The -usb switch installs what the chipset has by default.  On
"pc" (piix4 southbridge) this is only uhci.  On "q35" (ich9 southbridge)
this actually is a uhci/ehci companion setup.

> I would also want the -usbdevice host option to attach devices by bus
> compatibility to either uhci or ehci. The compatibility level is
> already examined in the libusb code so the information should be
> available.

Not needed.  With the companion setup you'll have a usb bus which can
handle both usb1 and usb2 devices.

If the guest is new enough that it has drivers you can also simply use
xhci.

cheers,
  Gerd