reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://github.com/esmil/linux/commit/52b502637f663a122417fde5416982e137148c64
        git remote add esmil https://github.com/esmil/linux
        git fetch --no-tags esmil d1-6.11.y
        git checkout 52b502637f663a122417fde5416982e137148c64
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/iommu/