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/avpatel/linux/commit/4423be73ba644a89e48da1cebbdf901f04b801f3
        git remote add avpatel https://github.com/avpatel/linux.git
        git fetch --no-tags avpatel riscv_acpi_b2_v7_611_rc1_full
        git checkout 4423be73ba644a89e48da1cebbdf901f04b801f3
        # 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/tty/serial/8250/