reproduce (this is a W=1 build):
        # https://github.com/frank-w/BPI-R2-4.14/commit/73d017d2081914dda668e77020506189e450daba
        git remote add frank-w-bpi-r2-4.14 https://github.com/frank-w/BPI-R2-4.14
        git fetch --no-tags frank-w-bpi-r2-4.14 6.12-rsslro
        git checkout 73d017d2081914dda668e77020506189e450daba
        # 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