reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/jimc/linux/commit/03a5021c51f56725837f7c18a6704ea25632fd24
        git remote add jimc https://github.com/jimc/linux.git
        git fetch --no-tags jimc dd-classmap-fix-v4h
        git checkout 03a5021c51f56725837f7c18a6704ea25632fd24
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash