reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        git remote add masahiroy-kbuild https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
        git fetch masahiroy-kbuild for-next
        git checkout masahiroy-kbuild/for-next
        b4 shazam https://lore.kernel.org/r/20240826124802.1552738-1-masahiroy@kernel.org
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash