reproduce (this is a W=1 build):
        # https://github.com/koverstreet/bcachefs/commit/7cd4e8f9f8f13d9c5a2bbc98b80ca164430d6062
        git remote add koverstreet-bcachefs https://github.com/koverstreet/bcachefs
        git fetch --no-tags koverstreet-bcachefs bcachefs-debug
        git checkout 7cd4e8f9f8f13d9c5a2bbc98b80ca164430d6062

        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=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=openrisc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=openrisc SHELL=/bin/bash