reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c20d3fa7049144f519b21616e6020e6939822145
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout c20d3fa7049144f519b21616e6020e6939822145
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 olddefconfig
        ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 SHELL=/bin/bash drivers/