[compiz] compiz segfaults on starting second X server / suspend to ram

[Vasek Potocek]

> 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 :-)