Aha progress.

(gdb) bt full
#0  XISendDeviceHierarchyEvent (flags=0xbfb2d73c) at ../../Xi/xichangehierarchy.c:73
        ev = 0x0
        info = <value optimized out>
        dummyDev = {public = {devicePrivate = 0x0, processInputProc = 0, realInputProc = 0, enqueueInputProc = 0, 
            on = 0}, next = 0x0, startup = 0, deviceProc = 0, inited = 0, enabled = 0, coreEvents = 0, deviceGrab = {
            grabTime = {months = 0, milliseconds = 0}, fromPassiveGrab = 0, implicitGrab = 0, activeGrab = {
              next = 0x0, resource = 0, device = 0x0, window = 0x0, ownerEvents = 0, keyboardMode = 0, 
              pointerMode = 0, grabtype = GRABTYPE_CORE, type = 0 '\000', modifiersDetail = {exact = 0, pMask = 0x0}, 
              modifierDevice = 0x0, detail = {exact = 0, pMask = 0x0}, confineTo = 0x0, cursor = 0x0, eventMask = 0, 
              deviceMask = 0, xi2mask = {"\000\000" <repeats 42 times>}}, grab = 0x0, activatingKey = 0 '\000', 
            ActivateGrab = 0, DeactivateGrab = 0, sync = {frozen = 0, state = 0, other = 0x0, event = 0x0}}, 
          type = 0, xinput_type = 0, name = 0x0, id = 0, key = 0x0, valuator = 0x0, button = 0x0, focus = 0x0, 
          proximity = 0x0, absolute = 0x0, kbdfeed = 0x0, ptrfeed = 0x0, intfeed = 0x0, stringfeed = 0x0, bell = 0x0, 
          leds = 0x0, xkb_interest = 0x0, config_info = 0x0, unused_classes = 0x0, saved_master_id = 0, 
          devPrivates = 0x0, unwrapProc = 0, spriteInfo = 0x0, u = {master = 0x0, lastSlave = 0x0}, last = {
            valuators = {0 <repeats 36 times>}, remainder = {0 <repeats 36 times>}, numValuators = 0, slave = 0x0}, 
          properties = {properties = 0x0, handlers = 0x0}, transform = {m = {{0, 0, 0}, {0, 0, 0}, {0, 
                1.5236786157049496e-285, 2.179289842072959e-311}}}, xtest_master_id = 150345912}
        dev = <value optimized out>
        i = <value optimized out>
#1  0x08085b04 in DisableDevice (dev=0xa6e0830, sendevent=1 '\001') at ../../dix/devices.c:507
        prev = <value optimized out>
        other = <value optimized out>
        enabled = 0 '\000'
        flags = {0, 0, 0, 0, 128, 0 <repeats 35 times>}
#2  0x08085d33 in RemoveDevice (dev=0xa6e0830, sendevent=1 '\001') at ../../dix/devices.c:1057
        prev = <value optimized out>
        tmp = <value optimized out>
        next = <value optimized out>
        ret = 8
        screen = <value optimized out>
        deviceid = 4
        initialized = 1
        flags = {0 <repeats 40 times>}
#3  0x080bd6fd in DeleteInputDeviceRequest (pDev=0xa6e0830) at ../../../../hw/xfree86/common/xf86Xinput.c:961
        pInfo = 0x0
        drv = 0x0
        isMaster = <value optimized out>
#4  0x08082bb3 in CloseDeviceList (listHead=0x8208104) at ../../dix/devices.c:966
        freedIds = {0, 0, 1, 1, 1, 0 <repeats 35 times>}
        dev = <value optimized out>
        i = <value optimized out>
#5  0x080831e7 in CloseDownDevices () at ../../dix/devices.c:994
        dev = 0x0
#6  0x0809dbd0 in SigAbortServer (signo=11) at ../../os/log.c:411
No locals.
#7  0x0809e671 in FatalSignal (signo=11) at ../../os/log.c:541
        beenhere = 1
#8  0x080a4bfd in OsSigHandler (signo=11, sip=0xbfb2dabc, unused=0xbfb2db3c) at ../../os/osinit.c:154
No locals.
#9  <signal handler called>
No symbol table info available.
#10 0x00125689 in pixman_image_set_has_client_clip (image=0x0, client_clip=1) at ../../pixman/pixman-image.c:530
No locals.
#11 0x0081aa38 in create_bits_picture (pict=0xb82cf98, has_clip=1, xoff=0xbfb2df6c, yoff=0xbfb2df68, is_alpha_map=0)
    at ../../fb/fbpict.c:188
        bits = <value optimized out>
        image = 0x0
        pixmap = <value optimized out>
        stride = <value optimized out>
        bpp = <value optimized out>
#12 image_from_pict_internal (pict=0xb82cf98, has_clip=1, xoff=0xbfb2df6c, yoff=0xbfb2df68, is_alpha_map=0)
    at ../../fb/fbpict.c:311
        image = 0x0
#13 0x0081ac81 in fbComposite (op=3 '\003', pSrc=0xa88f5c0, pMask=0xa88f628, pDst=0xb82cf98, xSrc=792, ySrc=22, 
    xMask=792, yMask=22, xDst=995, yDst=0, width=22, height=22) at ../../fb/fbpict.c:63
        src = <value optimized out>
        mask = 0x0
        dest = <value optimized out>
#14 0x00387b86 in uxa_check_composite (op=3 '\003', pSrc=0xa88f5c0, pMask=0xa88f628, pDst=0xb82cf98, xSrc=792, 
    ySrc=22, xMask=792, yMask=22, xDst=995, yDst=0, width=22, height=22) at ../../uxa/uxa-unaccel.c:371
        screen = <value optimized out>
        __FUNCTION__ = "uxa_check_composite"
#15 0x003843b0 in uxa_composite (op=3 '\003', pSrc=0xa88f5c0, pMask=0xa88f628, pDst=0xb82cf98, xSrc=792, ySrc=22, 
    xMask=792, yMask=22, xDst=995, yDst=0, width=22, height=22) at ../../uxa/uxa-render.c:1712
        uxa_screen = 0x3
        ret = <value optimized out>
        saveSrcRepeat = 768
        saveMaskRepeat = 0
        region = {extents = {x1 = -10896, y1 = 2696, x2 = 960, y2 = 0}, data = 0x18}
        tx = 0
        ty = 0
#16 0x0812c312 in damageComposite (op=3 '\003', pSrc=0xa88f5c0, pMask=0xa88f628, pDst=0xb82cf98, xSrc=792, ySrc=22, 
    xMask=792, yMask=22, xDst=995, yDst=0, width=22, height=22) at ../../../miext/damage/damage.c:613
        pScreen = <value optimized out>
        ps = 0xa644f18
        pScrPriv = 0xa6451f0
#17 0x08127c0b in CompositePicture (op=<value optimized out>, pSrc=0xa88f5c0, pMask=0xa88f628, pDst=0xb82cf98, 
    xSrc=792, ySrc=22, xMask=792, yMask=22, xDst=995, yDst=0, width=22, height=22) at ../../render/picture.c:1705
        ps = 0xa644f18
#18 0x0811ff79 in ProcRenderComposite (client=0xa7f8000) at ../../render/render.c:728
        pSrc = 0xa88f5c0
        pMask = 0xa88f628
        pDst = 0xb82cf98
        stuff = <value optimized out>
#19 0x0811cc63 in ProcRenderDispatch (client=0xa7f8000) at ../../render/render.c:2058
        stuff = <value optimized out>
#20 0x08070ab7 in Dispatch () at ../../dix/dispatch.c:431
        clientReady = 0xa801a80
        result = <value optimized out>
        client = 0xa7f8000
        nready = 0
        icheck = 0x8207c38
        start_tick = 37960
#21 0x0806284c in main (argc=9, argv=0xbfb2e484, envp=0xbfb2e4ac) at ../../dix/main.c:287
        i = <value optimized out>
        alwaysCheckForInput = {0, 1}
(gdb)