• Pine H64
• Orange Pi 3 LTS

• See the Allwinner boot process page for details how the board starts.
• See that same page for details how to modify a GENERICSD image for use with a Pine H64.

For the quickest of quick-starts without understanding, follow these steps:

• Obtain a bootable – for some other SBC – aarch64 image, such as FreeBSD-13.0-RELEASE-arm64-aarch64-ROCK64.img
• Install sysutils/u-boot-pine-h64
• Write the bootable image to a micro-SD card
• Write the u-boot code to the micro-SD card
• Place card in the Pine H64 SD-card slot and power on the board

dd if=FreeBSD-13.0-RELEASE-arm64-aarch64-ROCK64.img \
  of=/dev/da0 bs=1M conv=notrunc
dd if=/usr/local/share/u-boot/u-boot-pine-h64/u-boot-sunxi-with-spl.bin \
  of=/dev/da0 bs=128k seek=1 conv=sync