reproduce (this is a W=1 build):
        # https://github.com/isilence/linux/commit/82e6260191c8e37a99dec6445e1f1ff1e0394ef3
        git remote add isilence https://github.com/isilence/linux
        git fetch --no-tags isilence zc/rx-latest
        git checkout 82e6260191c8e37a99dec6445e1f1ff1e0394ef3
        # 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