Comment 21 for bug 181176

Forwarded from https://launchpad.net/bugs/181176, also reported on Debian http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=454304

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When launching X at anytime, usally right off the start. Ie right after X launches and splash screen occurs.

 /usr/bin/X goes into infinate loop consuming 99% CPU.

Verified by booting to single user, starting sshd, and letting boot. As soon as screen goes blank,
login via ssh and run top.

This occurs on a Toshiba Satellite Laptop 1800 exact model PS181C BIOS version 1.2 (floppy is dead, cannot upgrade BIOS)

Other reports of similair problem on FORUM and at following link with Debian Kernel:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=454304

Did
dpkg -i xserver-xorg-core-dbg_1.3.0.0.dfsg-12ubuntu8_i386.deb

and attached gdb to /usr/bin/X11 process. The following is the backtrace, repeated numerous times:

<snip>
(gdb) bt full
#0 x86emuOp_opc80_byte_RM_IMM (op1=128 '\200')
    at ../../../../hw/xfree86/int10/../x86emu/ops.c:5205
        mod = <value optimized out>
        rl = <value optimized out>
        rh = <value optimized out>
        destreg = <value optimized out>
        imm = <value optimized out>
        destval = <value optimized out>
#1 0xb7bd11b3 in X86EMU_exec ()
    at ../../../../hw/xfree86/int10/../x86emu/decode.c:122
        op1 = <value optimized out>
#2 0xb7bbd825 in xf86ExecX86int10 (pInt=0x8217870)
    at ../../../../hw/xfree86/int10/xf86x86emu.c:40
        sig = 0
#3 0xb7bd93f9 in vbeDoEDID (pVbe=0x8217848, pDDCModule=0x0)
    at ../../../../hw/xfree86/vbe/vbe.c:190
        pMonitor = <value optimized out>
        pModule = (pointer) 0x1
        DDC_data = <value optimized out>
#4 0xb7c0aa20 in TRIDENTSwitchMode ()
   from /usr/lib/xorg/modules/drivers//trident_drv.so
No symbol table info available.
#5 0x080a8e54 in InitOutput (pScreenInfo=0x8202a80, argc=10, argv=0xbf9e45f4)
    at ../../../../hw/xfree86/common/xf86Init.c:601
        i = <value optimized out>
        j = -1208328589
        k = <value optimized out>
        scr_index = <value optimized out>
        modulelist = <value optimized out>
        optionlist = (pointer *) 0x82115e0
        layout = <value optimized out>
        screenpix24 = <value optimized out>
        pix24 = <value optimized out>
        pix24From = <value optimized out>
        autoconfig = <value optimized out>
        generation = 1
#6 0x08076ceb in main (argc=10, argv=0xbf9e45f4, envp=0xbf9e4620)
    at ../../dix/main.c:370
        i = <value optimized out>
        error = 136217184
        xauthfile = <value optimized out>
        alwaysCheckForInput = {0, 1}
--

adding option NoDDC makes it work ok.