reproduce (this is a W=1 build):
        # https://github.com/jimc/linux/commit/4737e39b87dcdb3be9f9f5cdba373db19d0f6b38
        git remote add jimc https://github.com/jimc/linux.git
        git fetch --no-tags jimc dd-fix-9p
        git checkout 4737e39b87dcdb3be9f9f5cdba373db19d0f6b38
        # 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 lib/