reproduce (this is a W=1 build):
        # https://github.com/jimc/linux/commit/f5a1c2c15cfd150a90470a1fefc12568fbce7441
        git remote add jimc https://github.com/jimc/linux.git
        git fetch --no-tags jimc dd-cached-prefix
        git checkout f5a1c2c15cfd150a90470a1fefc12568fbce7441

        # 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 lib/