reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # clang-21 might not be officially released. Try a lower version if installation fails.
        git remote add tnguy-next-queue https://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue.git
        git fetch tnguy-next-queue dev-queue
        git checkout tnguy-next-queue/dev-queue
        b4 shazam https://lore.kernel.org/r/e199da76-00d0-43d3-8f61-f433bc0352ad@jacekk.info
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash drivers/net/ethernet/intel/e1000/