Hi,

Step 4:
Look into getting usb-2.0 support into qemu

Have you looked at xHCI + usb 3.0?

I think it would be a good idea to do that to make sure the redirection protocol can handle usb3 just fine. In a few years usb3 will be everythere, and when designing something now we should make sure it works nicely with usb3.

I had a brief look at the xHCI specs. It looks pretty nice from a emulation point of view. It is fully event driven design. It does more in hardware than UHCI+EHCI (it has to to reach the speeds without keeping the cpu 100% busy ;) IIRC the guest can just hand a ring buffer to the xHCI for iso xfers, no need to fiddle with usb packets manually. This is nice as it probably allows a quite efficient emulation. I think it is good for usb redirection too. Also xHCI handles all usb devices, so the UHCI/EHCI split for USB 1.1/2.0 devices which is quite nasty to emulate isn't there.

Jumping from USB 1.1 straight to USB 3.0 looks quite attractive from a emulation point of view, only problem with that is guest support, we can't (yet) expect guests to handle usb3 out-of-the-box. Also the qemu usb subsystem needs some work to handle usb3 nicely.

cheers,
  Gerd

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