XVideo vs. i855GM

[denbrok%uni-bonn.de@localhost]

Hello,

I'm running a recent NetBSD/i386 5.0_STABLE on a ThinkPad R50e,
which has an Intel i855GM IGD built in. I'd like to have hardware
acceleration for video playback but have not been successful so
far. I tried both native and pkgsrc Xorg. Both seem to be unable
to allocate sufficient memory. A web search suggested that DRI
might be rquired in this case, so I compiled a kernel with drm
enabled. I'm not sure whether it is considered supported on this
chipset, the manpage just mentioning i915 and i945 chipsets, however
the driver also matches the i855GM, and it works on Linux and
OpenBSD, so I tried anyway.

The result is that with DRI enabled, X starts up but doesn't display
anything. The keyboard seems locked; capslock, for instance, does
not toggle the corresponding LED, and I can't seem to get out of
X any way else than by pressing the power button. However, doing
so yields a clean shutdown, so X didn't lock up the machine
completely. I've put logs up at

http://www.uni-bonn.de/~denbrok/messages (with hw.dri.debug=1)

and 

http://www.uni-bonn.de/~denbrok/Xorg.0.log

in case anyone would like to take a look at it.

What I personally find suspicious is that Xorg.0.log has

(WW) intel(0): xf86AllocateGARTMemory: allocation of 1536 pages failed
        (Cannot allocate memory)
(WW) intel(0): Allocation error, framebuffer compression disabled
(WW) intel(0): xf86AllocateGARTMemory: allocation of 10 pages failed
        (Cannot allocate memory)

which happens both with and without DRI.

I'd be thankful for diffs to test (also against HEAD) or generally
any suggestions, even if it's just a note that i855GM isn't supposed
to be supported at all.

TIA,

Dennis den Brok