reproduce (this is a W=1 build):
        git remote add opencloudos https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
        git fetch --no-tags opencloudos next
        git checkout 9a447c5cb97d4648c380d9e26ffc6c9a99c05f69
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash net/core/