[compiz] compiz segfaults on starting second X server / suspendto ram

[David Reveman]

On Thu, 2007-05-17 at 01:25 +0200, Vasek Potocek wrote:
> > Hello,
> > when I start a second X server or when I suspend (and resume) to ram 
> > compiz crashes.
> > I tryed to debug this but its impossible to run gdb on compiz (=freeze). 
> > This happens with current git, but If I remember correctly not with 
> > 0.3.6 (and git versions < 0.5.0 but I don't know when it started to happen).
> > any ideas?
> 
> It is possible to debug compiz using gdb, you just can't run gdb in a terminal drawn by compiz. The simplest way is to 
> run it remotely through ssh. If you don't have another computer at your disposal, it's still possible to run gdb+compiz 
> on another VT, but you'll need to utilize the kernel's "Magic SysRq key" to escape from the freeze (to get back to the 
> console). You can find more info on both ways (plus one more which doesn't seem to be much reliable) on these links:
> 
> http://forum.compiz.org/viewtopic.php?p=111
> http://www.ubaight.com/pipermail/compcomm/2007-May/000639.html
> 
> [Thanks to the author of the latter post! I haven't heard about the key combination before.]
> 
> I'd add that the SysRq key combinations may not be available by default, it depends on kernel compiling configuration 
> and it can be turned on/off in addition. I don't know the various kernels, see your kernel documentation for details. 
> For example, on my Fedora Core 6, the support is compiled in, but must be turned on as described in 
> /usr/share/doc/kernel-doc-2.6.20/Documentation/sysrq.txt.
> And the situation is still a bit more tricky with nVidia because of its "VT-switching bug" (I may be wrong here), I 
> solved this by switching to the X VT very very fast after the run command :-)

Most of the time it's enough to have compiz dump a core file and load it
in gdb to see what caused a crash. I use this 95% of the time to track
down crashes in compiz.

- David