State of Zaphod dual screen support

[David Mohr]

On Sun, Feb 28, 2010 at 11:37 PM, Peter Hutterer
<peter.hutterer at who-t.net> 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.

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.

The strace output does not seem particularly useful to me, but maybe
I'm wrong. I just get over and over:
clock_gettime(CLOCK_MONOTONIC, {46551, 535857566}) = 0
rt_sigprocmask(SIG_BLOCK, [ALRM CHLD TSTP TTIN TTOU VTALRM WINCH IO],
[IO], 8) = 0
rt_sigprocmask(SIG_SETMASK, [IO], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [IO], 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [IO], 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [IO], 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [IO], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [], 8)  = 0
clock_gettime(CLOCK_MONOTONIC, {46551, 536167924}) = 0
rt_sigprocmask(SIG_BLOCK, [ALRM CHLD TSTP TTIN TTOU VTALRM WINCH IO],
[IO], 8) = 0
rt_sigprocmask(SIG_SETMASK, [IO], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [IO], 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [IO], 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [IO], 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [IO], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [IO], [], 8)  = 0

Thanks,
~David