reproduce (this is a W=1 build):
        # https://github.com/morimoto/linux/commit/92dabc48c39c54d73848ab0de6e901c844dbc954
        git remote add morimoto https://github.com/morimoto/linux
        git fetch --no-tags morimoto renesas-lts/v6.18-rc7-2025-11-28-x5h-ironhide
        git checkout 92dabc48c39c54d73848ab0de6e901c844dbc954

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # 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 drivers/mailbox/ drivers/net/