[daneel_w]

That's great. Do you know where I can find instructions on how to flash Tow-Boot to the SPI and how to configure it?

Add.: never mind, I found that Tow-Boot has excellent documentation for the whole procedure. Thanks for the heads-up on Tow-Boot.

[peanutbox]

Tow-Boot is great, and slowly being adopted by distributions (typically mobile distributions) as the way to do firmware/booting on aarch64.