So far I have only done this with a Cubieboard2, using the CubieTruck image. It should work on the CT itself, and other A20 boards that have a sata connector.
First there is some problem with the 2016.09.01 uboot for booting from sata. Don't know what it is, but after a brief conversation on the Fedora-arm list and the uboot list, I tried the uboot in F26 which is 2016.11 and that works. It is really quite simple:
dd your Cubie image onto your HD. Connect the HD to the sata port on the Cubie.
dd the uboot bin pulled from a Fedora26 image (or some other source for 2016.11) onto a smallish mSD card (I use a 4GB one that costs 1/2 that of a 16GB card). This card MUST have NO partitions. Just the uboot. Insert the mSD into the Cubie.
Boot.
You are on your way.
This, of course is very important. To run a production OS on a sata HD, and not a mSD card, and perhaps even a USB HD. You can use a SSD drive if you want to spend the money.
Bob
P.S. Next step is to turn this into a simple web server to replace the current medon.htt-consult.com server that keeps crashing with disk I/O problems (so much for better reliability with HDs!).
P.P.S. Feel free to add this to the Wiki. :)