reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/commit/?id=f2be51ec3aba541721c2baa65d272553d0fe961c
        git remote add cel https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux
        git fetch --no-tags cel nfsd-testing
        git checkout f2be51ec3aba541721c2baa65d272553d0fe961c

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc SHELL=/bin/bash fs/nfs_common/