Lockups When Logging Out

Daniel Kasak dan at entropy.homelinux.org
Sun Jun 4 22:14:38 PDT 2006

David M. Carney wrote:

> Using xorg 7.0 on Ubuntu Linux 6.06. Video device (on board) is Radeon 
> XPRESS 200. It shares system memory.
> When I use the fglrx (ATi 3d accelerated driver) I get hard lockups when 
> I try to terminate my xsession. Screen goes black and the keyboard is 
> unresponsive as in I cannot change the Num Lock status, etc. 
> ctrl-alt-backspace does nothing. If I try to use ctrl-alt-backspace from 
> an X session, I get the lockup, also.
> If I change the the non-3d accelerated ATi driver, the lockups go away 
> and all is well, excepting of course I no longer have 3d acceleration.

Your one-and-only 'fix' is to not use ATI's drivers. As you've 
discovered, they lock the system hard when exiting X or dropping to a 

You can use xorg's 2D driver for the XPRESS chips. There is no 3D 
support. If you want 3D support, you'll just have to live with lockups.

What I do is compile my kernel with the 'magic SysRq key' option 
enabled, and then before I exit X or drop to a console, I hit the keys:


( Son Uva Bitch ). ie hold down the ALT and SysRq keys, and hit S, then 
U, then B.

This leaves the disk in a sane state so if the system locks, I won't 
loose all my data when I cut the power and boot up again.

ATI claimed that the very latest driver update has fixed these lockups, 
but it's still happening on mine ( X700 mobility ).


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