reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/zen-kernel/zen-kernel/commit/0ce6427b65aca6bfe66b7301a9c15f2f7ac96685
        git remote add zen https://github.com/zen-kernel/zen-kernel
        git fetch --no-tags zen 6.16/prjc
        git checkout 0ce6427b65aca6bfe66b7301a9c15f2f7ac96685
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/sched/