We find there is another device id set for B43 chipset. After adding the device
id 4E90/4E92 beside 4E40/4E42, the machine works fine with the same
modification in xserver-xorg-video-intel.
After reporting to freedesktop bugzilla[1], Chris Wilson said the patch is
queued for adding this id set and now the adding-ID patch is accepted in
mainline kernel[2].
I tried to port on .32 stable kernel but lucid has .33 drm and lots modification
between these two version. So, I make the backport patches against current lucid
checkout.
These patches are available in the git repository at:
git://kernel.ubuntu.com/ikepanhc/public.git lp640214lucid