reproduce (this is a W=1 build):
        git remote add hverkuil-media-tree git://linuxtv.org/hverkuil/media_tree.git
        git fetch --no-tags hverkuil-media-tree vivid-kthread
        git checkout 61319ac7d6157a0f4d6f782749b820988e22fdf2
        # 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