(gdb) bt full
#0  0xb7c05c44 in SavageDoAdjustFrame (pScrn=0x8207df8, x=0, y=0, crtc2=0) at ../../src/savage_driver.c:3949
	psav = (SavagePtr) 0x8208f80
	currentMode = (DisplayModePtr) 0x0
	address = 0
	top = 0
	left = 0
	tile_height = 16
	tile_size = 2048
#1  0xb7c05a96 in SavageAdjustFrame (scrnIndex=0, x=0, y=0, flags=0) at ../../src/savage_driver.c:3903
	pScrn = (ScrnInfoPtr) 0x8207df8
	psav = (SavagePtr) 0x8208f80
#2  0xb7c05766 in SavageModeInit (pScrn=0x8207df8, mode=0x820a590) at ../../src/savage_driver.c:3818
	hwp = (vgaHWPtr) 0x82088a8
	psav = (SavagePtr) 0x8208f80
	width = 0
	dclk = 25175
	i = 0
	j = 0
	m = 0
	n = 0
	r = 0
	tmp = 0 '\0'
	new = (SavageRegPtr) 0x8209028
	vganew = (vgaRegPtr) 0x8208be4
	vgaCRIndex = 980
	vgaCRReg = 981
	vgaIOBase = 976
	refresh = 0
	newmode = 0
	newrefresh = 0
#3  0xb7c05e6f in SavageSwitchMode (scrnIndex=0, mode=0x820a590, flags=0) at ../../src/savage_driver.c:3993
	pScrn = (ScrnInfoPtr) 0x8207df8
	psav = (SavagePtr) 0x8208f80
	success = 0
#4  0x080f8163 in xf86CursorSwitchMode (index=0, mode=0x820a590, flags=0) at ../../../../hw/xfree86/ramdac/xf86Cursor.c:239
	ret = 0
	pScreen = (ScreenPtr) 0x0
	ScreenPriv = (xf86CursorScreenPtr) 0x82230d0
#5  0x080ca773 in CMapSwitchMode (index=0, mode=0x820a590, flags=0) at ../../../../hw/xfree86/common/xf86cmap.c:484
No locals.
#6  0x080bf47e in xf86SwitchMode (pScreen=0x820ac30, mode=0x820a590) at ../../../../hw/xfree86/common/xf86Cursor.c:236
	pScr = (ScrnInfoPtr) 0x8207df8
	pCursorScreen = (ScreenPtr) 0x820ac30
	Switched = 1
	px = <value optimized out>
	py = <value optimized out>
#7  0x080c7c8d in VidModeSwitchMode (scrnIndex=0, mode=0x820a590) at ../../../../hw/xfree86/common/xf86VidMode.c:372
	pScrn = (ScrnInfoPtr) 0x8207df8
	pTmpMode = (DisplayModePtr) 0x820a3a0
	retval = 136347128
#8  0xb7c9fc4a in ProcXF86VidModeSwitchToMode (client=0x84728a8) at ../../../../../hw/xfree86/dixmods/extmod/xf86vmode.c:1255
	stuff = (xXF86VidModeSwitchToModeReq *) 0xbf99e1a0
	newstuff = {reqType = 120 'x', xf86vidmodeReqType = 141 '\215', length = 9, screen = 0, dotclock = 25175, hdisplay = 640, hsyncstart = 656, hsyncend = 752, htotal = 800, hskew = 0, vdisplay = 480, vsyncstart = 490, vsyncend = 492, vtotal = 525, pad1 = 47051, flags = 10, reserved1 = 138881192, reserved2 = 3214533096, reserved3 = 3083474372, privsize = 0}
	mode = (pointer) 0x820a590
	len = <value optimized out>
	dotClock = 25175
	ver = <value optimized out>
#9  0x0814bbce in XaceCatchExtProc (client=0x84728a8) at ../../Xext/xace.c:299
	major = 135
	ext = <value optimized out>
#10 0x08088cbf in Dispatch () at ../../dix/dispatch.c:457
	result = <value optimized out>
	client = (ClientPtr) 0x84728a8
	nready = 0
	start_tick = 6180
#11 0x08070e05 in main (argc=11, argv=0xbf99e744, envp=Cannot access memory at address 0x8
) at ../../dix/main.c:477
	pScreen = <value optimized out>
	i = <value optimized out>
	error = -1080432780
	xauthfile = <value optimized out>
	alwaysCheckForInput = {0, 1}

(gdb) list
3944	     * because we align the viewport to the width and height of one tile
3945	     * we should update the locate of frame
3946	     */
3947	    pScrn->frameX0 = left;
3948	    pScrn->frameY0 = top;
3949	    pScrn->frameX1 = left + currentMode->HDisplay - 1;
3950	    pScrn->frameY1 = top + currentMode->VDisplay - 1;
3951	
3952	    if (psav->Chipset == S3_SAVAGE_MX) {
3953		if (!crtc2) {