Re: [Qemu-devel] USB passthrough in qemu

[Michal Suchanek]

On 12 June 2014 11:08, Gerd Hoffmann <address@hidden> wrote:
> 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.

In this particular case using q35 as platform should not pose a
problem, hopefully.

Also using the sendmail.cf like commandline works.

However, for the piix4 which is the default platform and is desirable
due to driver issues in many cases no simple way to instantiate the
companion setup and have qemu automagically attach the devices
correctly exists.

>
>> 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.

So this is taken care of already. Nice

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

What xhci hub is emulated?

Anyway, xhci drivers for Windows are a mess so this is not going to be
an option for a while I guess.

Thanks

Michal