ben@mercury ~ $ sudo bin/debug-proc X

GNU gdb 6.8
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This GDB was configured as "x86_64-pc-linux-gnu"...
cAttaching to program: /usr/bin/X, process 1997

Reading symbols from /usr/lib64/libpciaccess.so.0...done.
...
Loaded symbols for /usr/lib/libexpat.so.1
Reading symbols from /usr/lib64/xorg/modules/input/evdev_drv.so...done.
Loaded symbols for /usr/lib/xorg/modules/input//evdev_drv.so
0x00000037156bf8a3 in select () from /lib/libc.so.6
(gdb) 
(gdb) c
Continuing.

Program received signal SIGABRT, Aborted.
0x0000003715631185 in raise () from /lib/libc.so.6
(gdb) bt
#0  0x0000003715631185 in raise () from /lib/libc.so.6
#1  0x0000003715632630 in abort () from /lib/libc.so.6
#2  0x00007fe5a56c0955 in dri_ttm_fence_wait (fence=0xb94630)
    at intel_bufmgr_ttm.c:655
#3  0x00007fe5a5689bb4 in I830Sync (pScrn=0x9eda90) at i830_accel.c:187
#4  0x00007fe5a5695578 in i830_stop_ring (pScrn=0x9eda90, 
    flush=<value optimized out>) at i830_driver.c:1785
#5  0x00007fe5a569564b in I830LeaveVT (scrnIndex=<value optimized out>, 
    flags=<value optimized out>) at i830_driver.c:3131
#6  0x00000000004673ad in AbortDDX () at xf86Init.c:1302
#7  0x00000000004fa8f8 in AbortServer () at log.c:406
#8  0x00000000004faf65 in FatalError (
    f=0x7fe5a56cf0ba "Failed to map pixmap: %s\n") at log.c:552
#9  0x00007fe5a56b22b1 in I830EXAPrepareAccess (pPix=0xb291d0, 
    index=<value optimized out>) at i830_exa.c:501
#10 0x00007fe5a47cfebd in ExaDoPrepareAccess (pDrawable=0xdcd1e0, index=1)
    at exa.c:489
#11 0x00007fe5a47cffa8 in exaPrepareAccessReg (pDrawable=0xdcd1e0, index=1, 
    pReg=0x7fffae5b0600) at exa.c:509
#12 0x00007fe5a47d1811 in exaGetImage (pDrawable=0xdcd1e0, 
    x=<value optimized out>, y=<value optimized out>, w=1, h=1, format=2, 
    planeMask=4294967295, d=0xd697d0 "P\202�") at exa_accel.c:1374
#13 0x00000000004dff8e in miSpriteGetImage (pDrawable=0xdcd1e0, sx=599, 
---Type <return> to continue, or q <return> to quit---
    sy=599, w=1, h=1, format=2, planemask=4294967295, 
    pdstLine=0xd697d0 "P\202�") at misprite.c:281
#14 0x000000000044a24e in ProcGetImage (client=0xd60b90) at dispatch.c:2064
#15 0x000000000044c0d4 in Dispatch () at dispatch.c:451
#16 0x00000000004329bd in main (argc=9, argv=0x7fffae5b0918, 
    envp=<value optimized out>) at main.c:441
(gdb)