Re: [Xen-devel] [PATCH] libxl: add a vkbd device to HVM guests by default

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 27 Jun 2011, Ian Campbell wrote:
> On Mon, 2011-06-27 at 13:14 +0100, Stefano Stabellini wrote:
> > On Mon, 27 Jun 2011, Ian Campbell wrote:
> > > On Fri, 2011-06-24 at 17:29 +0100, Stefano Stabellini wrote:
> > > > PV on HVM drivers can connect to the vkbd device to receive mouse and
> > > > keyboard events from Qemu. The advantage over USB is that vkbd doesn't
> > > > require frequent wakeups in Qemu.
> > > 
> > > Do we need an unplug protocol in order to stop these frequent wakeups?
> > 
> > No, we just need to disable USB. The only reason to have USB is to have
> > USB tablet support (absolute mouse coordinates).
> 
> That means users need to be aware that they have the appropriate
> frontends and manually edit their guest config?

Consider that usb is already off by default, users need to add usb=1 to
the config file in order to enable it.
Also even with usb=0 everything will keep working as expected, only the
"mouse experience" will be worse.

So I don't see this as a particular problem either way, maybe we should
just add a note to the 4.2 xen release about the PV mouse and keyboard
protocol and why it is a good idea to disable usb.

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