U-Boot loader and related files for the FriendlyARM NanoPi-R4S (4GB/LPDDR4)

To install this bootloader on an sdcard just do:

dd if=/usr/local/share/u-boot/u-boot-nanopi-r4s/idbloader.img of=/path/to/sdcarddevice seek=64 bs=512 conv=sync
dd if=/usr/local/share/u-boot/u-boot-nanopi-r4s/u-boot.itb of=/path/to/sdcarddevice seek=16384 bs=512 conv=sync

WWW: https://www.denx.de/wiki/U-Boot