reproduce (this is a W=1 build):
        # https://github.com/paulmckrcu/linux/commit/2c4925768252397b03d47704f70891ce2b47e774
        git remote add paulmckrcu https://github.com/paulmckrcu/linux
        git fetch --no-tags paulmckrcu dev
        git checkout 2c4925768252397b03d47704f70891ce2b47e774

        # clang-24 might not be officially released. Try a lower version if installation fails.
        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=$HOME/0day COMPILER=clang-24 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=hexagon olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-24 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash kernel/rcu/