Re: [Xen-devel] [PATCH v6 2/2] xl: Add commands for usb hot-plug

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, Apr 25, 2013 at 12:57:50PM +0100, George Dunlap wrote:
> On 04/25/2013 12:38 PM, Ian Campbell wrote:
> >On Thu, 2013-04-25 at 11:16 +0100, George Dunlap wrote:
> >>>>+    for (i = 0; i < num; i++) {
> >>>>+        printf("%8s  ", 
> >>>>(dev[i].protocol==LIBXL_USB_PROTOCOL_PV)?"pv":"dm");
> >>>
> >>>You can use libxl_usb_protocol_to_string here.
> >>
> >>Could do, but I didn't necessarily want the long version ("devicemodel").
> >
> >TBH the more I think about it the more I think DM/DEVICEMODEL in this
> >interface is leaking an implementation detail, after all the user
> >doesn't really care who/what is emulating a USB controller.
> >
> >Protocol = {PV,OHCI,XHCI}?
> 
> As we covered before:
> 
> 1. I have no way of selecting OHCI vs XHCI at this point
>

https://github.com/qemu/qemu/blob/master/docs/usb2.txt

qemu -device usb-ehci,id=ehci \
     -device usb-tablet,bus=usb-bus.0 \
     -device usb-storage,bus=ehci.0,drive=usbstick

"This attaches a usb tablet to the UHCI adapter and a usb mass storage
device to the EHCI adapter."


http://lists.gnu.org/archive/html/qemu-devel/2012-05/msg04013.html
qemu $args -device nec-usb-xhci,id=xhci -device usb-tablet,bus=xhci.0

http://www.linux-kvm.com/content/qemu-kvm-11-adds-experimental-support-usb-30
qemu-kvm -device nec-usb-xhci,id=xhci -device 
usb-storage,bus=xhci.0,drive=usbstick


So it seems it's possible to create ehci/usb2.0 and xhci/usb3.0 controllers as 
needed,
and attach devices to both of them by specifying the virtual bus..


 
> 2. Even if I did, why should the caller have to keep track of what
> kind of USB hardware is exposed to the guest?  They should be able
> to just say "Add" and have stuff sorted out.
> 

Compatibility might be one reason why users want to specify specific virtual 
controller..
ie. some usb 2.0 devices don't work properly in usb 3.0 controllers, 
unfortunately..

-- Pasi


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