https://bugs.freedesktop.org/show_bug.cgi?id=54662
--- Comment #5 from Tony Thomas autonymous@gmail.com 2012-09-11 15:52:36 UTC --- (In reply to comment #4)
(In reply to comment #1)
Recent Ubuntu versions don't come with an xorg.conf file, and "sudo Xorg -configure" reports a fatal error, so I'm not sure how to generate a base file to tweak.
Recent versions of Ubuntu (and others) allow for snippets of Xorg.conf in either /etc/X11/xorg.conf.d, or (as in Ubuntu) /usr/share/X11/xorg.conf.d. Just make a new file, and add a section such as this:
#vi 50-mydevice.conf
Section "Device" Identifier "my-radeon-card" Option "NoAccel" "TRUE" EndSection