Finally I’ve managed to to make it work on both SD card and eMMC. I used Yocto with the latest mainline U-boot instead of Friendlyarm approach to build the image.
 
Thanks,
Mikhail
  
>Среда, 18 марта 2020, 21:01 +03:00 от Arti Zirk <arti.zirk@gmail.com>:
> 
>On N, 2020-03-12 at 15:53 +0300, Mikhail wrote:
>> The system (with Ubuntu 18) is installed on EMMC and it uses rockchip
>> u-boot as bootloader Have you looked into how Armbian has done support for this board?
>https://www.armbian.com/nanopi-neo4/
>  
 
 
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