reproduce (this is a W=1 build):
        # https://github.com/tobetter/linux/commit/61f45d975621becb00c0aef303769f10428b9cd8
        git remote add tobetter https://github.com/tobetter/linux
        git fetch --no-tags tobetter odroid-5.15.y
        git checkout 61f45d975621becb00c0aef303769f10428b9cd8
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um SUBARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash drivers/char/