reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install mips cross compiling tool for clang build
        # apt-get install binutils-mipsel-linux-gnu
        # https://github.com/jcmvbkbc/linux-xtensa/commit/08b8a525de25b35564cb9ae5f7b5ad1122a84fed
        git remote add jcmvbkbc-xtensa https://github.com/jcmvbkbc/linux-xtensa
        git fetch --no-tags jcmvbkbc-xtensa xtensa-6.13-esp32
        git checkout 08b8a525de25b35564cb9ae5f7b5ad1122a84fed
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash drivers/misc/