Latest -ati git breaks X. Bisected:

39eac3104c2f08b4d78aab3f88fd104301eb4711 is the first bad commit
commit 39eac3104c2f08b4d78aab3f88fd104301eb4711
Author: Ilija Hadzic <ihadzic@research.bell-labs.com>
Date:   Mon Sep 24 17:41:32 2012 -0400

    radeon/radeon_platform_probe: fix Zaphod mode breakage
    
    Using radeon_platform_probe function breaks the Zaphod mode because
    it attempts to call xf86AddEntityToScreen multiple times, but nobody
    calls xf86SetEntityShared prior to that. Consequently, calls for all
    but first device instance fail.
    
    Prior to introduction of platform bus, the logic was that the Probe
    function would make the entity sharable, which would cause Xserver
    to later make it shared prior to adding it to screen. With the
    platform bus loading, add to screen happens in the probe
    function so we have to make it shared there.
    
    Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com>

:040000 040000 42764e008e64efcf63a9324e859d73c292db20fd 36d1a97b0bc6add7eff8fab50757cf21eac1b1a2 M	src