reproduce (this is a W=1 build):
        git remote add drm-tip git://anongit.freedesktop.org/drm/drm-tip
        git fetch --no-tags drm-tip drm-tip
        git checkout a59bb8e436a090adb48ed2723fd6864cd82bf8c8
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash