This bug is a bit strange and it may not only be X who is to blame.

I have a panasonic CF-51 toughbook with
00:02.0 VGA compatible controller: Intel Corporation 82852/855GM Integrated Graphics Device (rev 02)
00:02.1 Display controller: Intel Corporation 82852/855GM Integrated Graphics Device (rev 02)

I enabled 3D acceleration and can play e.g. Quake3 with acceptable performance.

Since ~6 weeks i am using dialup via UMTS / bluetooth rfcomm interface, often combined with IPSEC tunnels. Since then, i get spurious lockups, usually when closing or opening the lid. These are hard lockups, usually the backlight stays off and sysrq does not work.

I can trigger it almost reliably when dialing in, leaving the connection open, closing the lid, waiting for 3 minutes, opening the lid. Machine crashed.

Often it even hangs if i close the ppp connection and remove the bluetooth dongle, and after that close and open the lid.

After educating another user over the "Experimental" nature of DRI, i remembered that i have it enabled also and decided to disable it. Since then, i had at least 5 successful lid close / open events and no hang. I will test during the holidays if disabling 3d is really a cure for this plague.

Note that i did not have to actually use the 3d engine, it was just enabled (and i915 loaded, of course). This happened with all kernels, starting from the 10.0 kernel to the HEAD KOTD (last tested last week).

I think there is some strange memory corruption happening somewhere in the networking, bluetooth and / or DRI code and this is then triggering the hard lockup.

Note that i do not need to use IPSEC, nor ipw2200 or other strange drivers to trigger this bug.

Taking Karsten into cc: because i discussed this problem with him and Olaf because he is the "victim" of my IPSEC bug that may intermix with this one, feel free to remove yourself from cc :-)

And of course i know that 3D is totally unsupported etc...