Re: [Xen-devel] [PATCH 3/3 v4] xenfb: Add [feature|request]-raw-pointer

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 12 Oct 2017, Paul Durrant wrote:
> > -----Original Message-----
> > From: Gerd Hoffmann [mailto:kraxel@xxxxxxxxxx]
> > Sent: 12 October 2017 10:26
> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; 'Stefano Stabellini'
> > <sstabellini@xxxxxxxxxx>; Anthony Perard <anthony.perard@xxxxxxxxxx>
> > Cc: qemu-devel@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx; Owen Smith
> > <owen.smith@xxxxxxxxxx>
> > Subject: Re: [Xen-devel] [PATCH 3/3 v4] xenfb: Add [feature|request]-raw-
> > pointer
> > 
> >   Hi,
> > 
> > > It's probably OS specific though. I guess the behaviour changed
> > > because the OS favours absolute pointing devices over relative ones
> > > and how it has two absolute ones to choose from. How it reconciles
> > > those, who knows?
> > 
> > Typically hid emulation calls qemu_input_handler_activate() when the
> > guest initializes the device, which moves the device to the top of the
> > priority list.
> > 
> > Visible effect on a typical guest with ps/2 mouse and usb-tablet is
> > that qemu switches from relative mode (mouse) to absolute mode (tablet)
> >  when the guest loads the usb hid driver.
> > 
> > I suspect pvmouse is doing the same thing.  So it may simply depend on
> > guest driver load order whenever pvmouse or usb-tablet is used.
> > 
> > Simplest fix is probably to only attach the device you plan to use to
> > the guest.  If you can't turn off pvmouse for xen guests then you might
> > want drop the qemu_input_handler_activate() call, so it behaves simliar
> > to the ps/2 mouse (is used in case no other pointer device is present).
> 
> Avoiding the activate call sounds reasonable and should avoid the behavioural 
> change.

+1

Owen, are you up for resubmitting the series with this small change?

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