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Tips to find the cause of a seg fault
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Date: 2010-12-01 (10:51)
From: oliver@f...
Subject: Re: [Caml-list] Tips to find the cause of a seg fault
On Wed, Dec 01, 2010 at 11:26:19AM +0100, Philippe Veber wrote:
> 2010/12/1 <>
> > Hi,
> >
> >
> > On Wed, Dec 01, 2010 at 09:32:16AM +0100, Philippe Veber wrote:
> > > Actually I was not confident I could extract a small program reproducing
> > the
> > > issue until ... you had me try ! I could get a very tiny example that
> > > behaves exactly the same, which does not involve opengl at all, only sdl.
> > > Here it is :
> > [...]
> >
> >
> > After installing some sdl-related packages, I could comopile the code.
> > So far it does not crash.
> >
> > What actions do create the segfault for you?
> >
> roll the mouse wheel up or down fast with the cursor on the window. However,
> I know that this problem does not occur everywhere, so you might well
> observe nothing ...

No crash happened.

Normally I'm very gifted to crash software.... by just looking at it.

If there is a bug, it will find me  ;)

Did you tried another X-driver?

In your valgrind printout there was mentioned "libnvidia".
And a crash seems to have been occured at that part:

> ==11306==    by 0x4215D5: camlHum__entry (in
> /home/pveber/hum/_build/src/hum.native)
> ==11306==    by 0xC5767A7: ???
> ==11306==
> ==11306== Conditional jump or move depends on uninitialised value(s)
> ==11306==    at 0x7695580: ??? (in
> /usr/lib/nvidia-current/
> ==11306==    by 0x1000000000000: ???
> ==11306==
> vex amd64->IR: unhandled instruction bytes: 0xFF 0xD8 0xC 0xF9 0xFF 0xD8
> ==11306== valgrind: Unrecognised instruction at address 0x4992cb.
> ==11306== Your program just tried to execute an instruction that Valgrind

So, please chack this. Maybe one of the free drivers does work better,
or maybe an update could help.

If you update your kernel, then you might also need to update the
X-drivers, because the nvidia stuff is non-free binary stuff,
and maybe some bindings don't work correctly with a new kernel.

I once experienced problems the other way around: crashing blender
with the free drivers, just by scaling into a view more and more,
and no crash with the non-free drivers.

This X11-driver part is really a desert...

...and even if you don't use OpenGL commands... the driver that you installed
and configured will be used nevretheless, and if there is something wrong, you
will get your crashes.

Look if the X11-driver-bindings are all up to date for the driver you use now,
and also try another X11-driver...