State of Zaphod dual screen support

Peter Hutterer peter.hutterer at
Mon Mar 1 14:38:05 PST 2010

On Mon, Mar 01, 2010 at 12:41:02AM -0700, David Mohr wrote:
> On Sun, Feb 28, 2010 at 11:37 PM, Peter Hutterer
> <peter.hutterer at> wrote:
> > On Sun, Feb 28, 2010 at 11:29:12PM -0700, David Mohr wrote:
> >> I'm part of the minory who currently uses a Zaphod style dual monitor
> >> setup with separate X screens for every monitor. When I recently
> >> upgraded from 7.4 to 7.5, some utilites which I adopted[1] which
> >> manipulate the mouse cursor started malfunctioning. My two X screens
> >> are setup to be "apart" so that the mouse does not pass between them,
> >> and I use my utilities to move the mouse between the two screens. But
> >> with 7.5 every now and then a condition is triggered where the mouse
> >> cursor will just continually jump from screen to screen, keeping the X
> >> server at 100% CPU. I cannot even shut it down using
> >> CTRL-ALT-Backspace.
> >>
> >> I've noticed comments in other threads on this mailing list that
> >> Zaphod mode is not really supported any more (for completeness' sake,
> >> I'm using the binary Nvidia drivers). So my question is, is there
> >> value in trying to track down the bug in Xorg which causes the mouse
> >> to jump back and forth?
> >
> > yes. I've seen this myself and I have not yet identified the issue. it's a
> > server bug and unrelated to the binary driver. If you can help track this
> > issue down, it would be much appreciated.
> Ok. Unfortunately I have not been able to find reliable conditions for
> triggering the bug. I'll try again and see what I can find.

i found using a wacom tablet with a xinerama setup and then switch back and
forth triggers it eventually. the problem is the "eventually" bit...

> Is there any way to get good information out of the running X instance
> once the bug has been triggered? I can only think of sending a signal
> to get a core dump, but then I'm not sure how much useful information
> that would contain.

once it happens, gdb in and single-stepping may be the only approach. a
backtrace would be great already, just to make sure if you're seeing the
same problem as I am.


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