Debian

Yu can download the prebuit image directly.

Baidu PanGoogle Drive

or you could use the rootfs-build-script from Rockchip to build rootfs yourselves.

Yocto

If you want to use Yocto to build your rootfs see yocto-user-guide for detail.

Buildroot

If you want to use Buildroot to build your rootfs see buildroot-user-guide for detail.