reproduce (this is a W=1 build):
        git remote add drm-misc git://anongit.freedesktop.org/drm/drm-misc
        git fetch --no-tags drm-misc for-linux-next
        git checkout 33d5ae6cacf46a043578d711ae7239bab55b4455
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/gpu/drm/i915/