Probably the reason is xinerama turned on, but it shouldn't crash anyway, at least report something, it's not nice to get broken X :( I'll test other versions and will play with xorg.conf to get more details soon.
Created attachment 177487 [details] xorg.conf That's my xorg.conf, there are 2 dualheaded ati cards, each uses MergedFB, there also is Xinerama on. x11-base/xorg-server is 1.3.0.6 with xineramainfo patch from here http://www.nvnews.net/vbulletin/showthread.php?t=85604&page=4 , which adds the XineramaInfo option line to ServerLayout section (it allows me to maximize windows to physical monitors, not MergedFB screens)
Checked 6.9.0, same crash. Trigger is xinerama on, presence of xineramainfo doesn't affect crashing. Part of crash message: Backtrace: 0: X(xf86SigHandler+0x6d) [0x47eb7d] 1: /lib/libc.so.6 [0x2b91d3c1f430] 2: X(RRCrtcSetRotations+0) [0x51faa0] Fatal server error: It's always the same except address in libc, it changes from crash to crash. I don't yet know if it's possible to use xrandr only without xinerama and xineramainfo for my needs. Crash is still awfull, at least I'd like to see a big warning that xinerama cause crash to >=6.8.0-r1 xf86-video-ati when it's updated from 6.6.3.
More complete crash message: Backtrace: 0: X(xf86SigHandler+0x6d) [0x47eb7d] 1: /lib/libc.so.6 [0x2b91d3c1f430] 2: X(RRCrtcSetRotations+0) [0x51faa0] Fatal server error: Caught signal 11. Server aborting
Also checked patch from http://bugs.gentoo.org/show_bug.cgi?id=240267, it doesn't help, for now I'd say >=6.8.0 isn't stable :(
*** This bug has been marked as a duplicate of bug 249156 ***
