reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # clang-21 might not be officially released. Try a lower version if installation fails.
        # https://github.com/AsahiLinux/linux/commit/ceb29a7a5af1b1f599f0614570b5bedb02ef9764
        git remote add asahilinux https://github.com/AsahiLinux/linux
        git fetch --no-tags asahilinux bits/000-devicetree
        git checkout ceb29a7a5af1b1f599f0614570b5bedb02ef9764
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash