Attach touch screen to a single display

Julian Ortiz julian.ortiz at
Thu Jun 17 21:28:00 PDT 2010

There is no problem about having a single large desktop... but I need to use
nvidia driver and as far as I understand it does not support Rand1.2.

The race condition is caused because xf86InputSetScreen is not thread safe?

About Peter Korsgaard matrix... where can I found it to take a look?


On Wed, Jun 16, 2010 at 3:21 AM, Peter Hutterer <peter.hutterer at>wrote:

> On Mon, Jun 14, 2010 at 05:10:40PM +0200, Julian Ortiz wrote:
> > Hello,
> > After looking for a way to make a touch screen works only in its display
> > (with nvidia configured as different XScreens) with no luck at all, I
> > started to look at the input modules source. I realizes that
> > the proprietary elo module calls to xf86XInputSetScreen, the function
> name
> > seems promising, so I just patch the evdev module to support several
> screens
> > by configuration and to call xf86InputSetScreen in the EvdevReadInput
> just
> > before the EvdevProcessEvent.
> >
> > The result seems to work but the behavior is very erratic and sometimes
> the
> > mouse/touch/keyboard get freezes and I need to restart X. And more
> strange,
> > after launch several OpenGL application the performance drops so, so much
> > (obviously without the patch it doesn't happen)
> >
> > Is xf86InputSetScreen the best approach to handle this?
> There's a race condition that can be triggered by xf86InputSetScreen() that
> ends up with a cursor jumping indefinitely between the two screens. This is
> likely the freeze you're seeing.
> There's unfortunately no good way to bind the device to a single screen
> right now. Peter Korsgaard input transformation matrix allows it for a
> RandR 1.2 setup but not for multiple protocol screens.
> Cheers,
>   Peter
> > Trying to find the module responsible for the mouse switch between
> different
> > display I saw references to something called SilkenMouse, but I can't
> find
> > any documentation about what is this. Any idea?
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