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/masahiroy/linux-kbuild.git/commit/?id=6b5747d07138f8109b1a150830f1d138de146ac2
        git remote add masahiroy-kbuild https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
        git fetch --no-tags masahiroy-kbuild kbuild
        git checkout 6b5747d07138f8109b1a150830f1d138de146ac2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 prepare