reproduce (this is a W=1 build):
        git remote add geert-renesas-drivers https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git
        git fetch geert-renesas-drivers renesas-clk
        git checkout geert-renesas-drivers/renesas-clk
        b4 shazam https://lore.kernel.org/r/20251002161728.186024-7-prabhakar.mahadev-lad.rj@bp.renesas.com
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=s390 SHELL=/bin/bash