reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git/commit/?id=4030decf42ca0da176fc1d5c556fc3f0035df6c9
        git remote add arnd-asm-generic https://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git
        git fetch --no-tags arnd-asm-generic master
        git checkout 4030decf42ca0da176fc1d5c556fc3f0035df6c9
        # 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 lib/