Backtrace:
0: /home/andy/Src/Xorg-git/modular/bin/Xorg (xorg_backtrace+0x3b) [0x80dc2ab]
1: /home/andy/Src/Xorg-git/modular/bin/Xorg (0x8048000+0x59da5) [0x80a1da5]
2: (vdso) (__kernel_rt_sigreturn+0x0) [0xffffe40c]
3: /home/andy/Src/Xorg-git/modular/bin/Xorg (xf86ChangeGamma+0x4b) [0x816517b]
4: /home/andy/Src/Xorg-git/modular/bin/Xorg (VidModeSetGamma+0x65) [0x81625c5]
5: /home/andy/Src/Xorg-git/modular/lib/xorg/modules/extensions/libextmod.so (0xb7c32000+0x85c2) [0xb7c3a5c2]
6: /home/andy/Src/Xorg-git/modular/bin/Xorg (0x8048000+0x24f60) [0x806cf60]
7: /home/andy/Src/Xorg-git/modular/bin/Xorg (0x8048000+0x1a675) [0x8062675]
8: /lib/libc.so.6 (__libc_start_main+0xd0) [0xb7c83380]
9: /home/andy/Src/Xorg-git/modular/bin/Xorg (0x8048000+0x1a271) [0x8062271]
Segmentation fault at address 0x16c

Fatal server error:
Caught signal 11 (Segmentation fault). Server aborting