reproduce (this is a W=1 build):
        git remote add hch-xfs git://git.infradead.org/users/hch/xfs
        git fetch --no-tags hch-xfs xfs-crc
        git checkout 4acc7ae85924f4d389a953ea0992c9e3b8735f0e

        # 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