State of Zaphod dual screen support

[Pat Kane]

I recently fixed a problem in an experimental ddx that had similar
symptoms.  It was caused by bug in my  DPMS code.

I tracked it down by using "gdb -p pid_of_X" to attach to the
borked X server and then single stepping the beast.

Pat
---


On Mon, Mar 1, 2010 at 1:41 AM, David Mohr <damailings at mcbf.net> wrote:
> 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
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