$ curl -fsSL http://deb.ayufan.eu/ayufan-rock64/linux-kernel/archive.key | sudo apt-key add -
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel stretch releases"
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel jessie releases"
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel xenial releases"
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel bionic releases"
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel stretch releases pre-releases"
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel jessie releases pre-releases"
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel xenial releases pre-releases"
$ sudo add-apt-repository "deb http://deb.ayufan.eu/ayufan-rock64/linux-kernel bionic releases pre-releases"
$ sudo apt-get update