As reported by Matthias Berndt in the Debian bug tracker, XKB appears to be causing segfaults in the X server. The version of the server he's using is from the 1.4.1 branch, along with the recent security fixes. As mentioned in the bug report, when he regenerated a new config file that's more minimal, he no longer got segfaults. A backtrace is attached to the original bug.
According to the reporter this started happening with the server-1.4-branch snapshot from 20080118, and didn't happen with the one from 20080105. The only xkb-related change between both versions seems to be 8a3acd3ec41b887b4aeaa0b2932265522c1e2836.
FWIW, I've also seen 2 users with problems like this until they remove XkbModel "latitude" from their xorg.conf.
Ken Bloom reported a similar backtrace in Debian bug #463194. He was doing
setxkbmap -I$HOME \
-layout us,.hebrew \
-option grp:toggle,grp_led:scroll \
-print | xkbcomp -I$HOME - :0
with .hebrew file available at http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=5;filename=.hebrew;att=2;bug=463194
Could this be fixed by 7018f280406eb0ef899a4046de274cfdd582881b ?
author Peter Hutterer <email@example.com>
Thu, 7 Feb 2008 05:18:04 +0000 (15:18 +1030)
xkb: when copying the keymap, make sure the structs default to 0/NULL.
It actually does help if a pointer is NULL rather than pointing to nirvana
when you're trying to free it lateron. Who would have thought?
That commit fixes the crashes completely here.
*** Bug 15250 has been marked as a duplicate of this bug. ***