[gentoo-user] DRI doesn't work with xorg 7.4 and an intel chipset Q35 board

Hi,
I've a (somewhat new) computer with an intel Q35 chipset graphics.
Until yesterday I ran the stable xorg-x11 version, with USE=dri and
USE=opengl enabled.
BUT as soon as I started a program which wanted to do something with
OpenGL (like google earth, amarok with openGL use flag, or just
glxgears),
the xorg-xserver crashed. Absolutely reliably.

I found a comment about the incomplete support for openGL/dri for i915
graphic cards in the stable xorg driver, so I upgraded to xorg-x11 7.4
(with a whole lot of unmasking).

Now I don't get a crash, BUT still dri don't work (didn't work earlier
on, too - but I have no traces).

I've loaded the drm module with debug=1, and found the syslog messages
(snipped):
[drm:i915_getparam] *ERROR* Unknown parameter 5
and

[drm:i915_initialize] *ERROR* can not ioremap virtual address for ring
buffer

In Xorg.0.log I found following warnings and errors:
(WW) intel(0): libpciaccess reported 0 rom size, guessing 64kB
and
(EE) intel(0): I830 Dma Initialization Failed

I've tried both XAA and EXA - didn't change a thing.

I've upgraded to 2.6.27-gentoo-r10 - no change.
xdriinfo says:
$xdriinfo
Screen 0: not direct rendering capable.

BUT:

$ glxinfo
name of display: :0.0
display: :0  screen: 0

direct rendering: Yes

What can I do now? 
What is going on here???

Puzzled,
Wolfgang