reproduce (this is a W=1 build):
        # https://github.com/thesofproject/linux/commit/5d1ad0198aca9adc1252497092b7c20ed3b72d45
        git remote add thesofproject https://github.com/thesofproject/linux
        git fetch --no-tags thesofproject topic/sof-dev
        git checkout 5d1ad0198aca9adc1252497092b7c20ed3b72d45
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um olddefconfig
        make W=1 O=build_dir ARCH=um SHELL=/bin/bash