Also interested in this. Was able to install using `sudo ./sunxi-fel -p spiflash-write 0 u-boot-sunxi-with-spl.bin`, where the u-boot image came from the Armbian I downloaded (scp'd it off). That makes use of a patch submitted to the sunxi-tools repo (https://github.com/linux-sunxi/sunxi-tools/pull/232), which does actually work.
It is quite happy to boot the image from SD card, and runs even when there is no SD card installed, which is great!
However, I don't see any SPI or mtdblock messages in dmesg, and naturally, none exist in /dev/. Am I missing something? Or is SPI not enabled currently for some reason?