Using gentoo-sources-2.6.16-r7 kernel. http://www.gentoo.org/doc/en/dri-howto.xml Seems at least one thing is missing from the guide: in order to emerge x11-drm one must first set something like VIDEO_CARDS="video_cards_radeon" in the /etc/make.conf file. Furthermore, when I simply set VIDEO_CARDS="radeon" as per the output of the emerge without any VIDEO_CARDS set, the x11-drm package did not compile. However it compiled successfully with VIDEO_CARDS="video_cards_radeon" None of these complications are hinted at in the guide. Still, even after the installation of the x11-drm package using VIDEO_CARDS="video_cards_radeon" the module was missing. No further hints as to what may be wrong are given in the howto.
*** This bug has been marked as a duplicate of 134087 ***