I tested the rock64 with a current miniroot63.fs. After wondering for quite a while why it stops after mounting the root I figured out that I just don't see any output anymore. OpenBSD seems to switch the baudrate at this stage from the initial 1500000 to 115200. I'm not sure if the initial value can be set, there is an option in u-boot for this afaik. After setting the right baudrate for the serial adapter I also saw output after the root filesystem was mounted. The native ethernet however seems to be dysfunctional. The interface is detected but you can't establish a connection. DHCP discover will fail, it sends some packages but never finishes setting up the connection. Also only the bottom USB 2 connector is working. When I attach an USB - ethernet adapter I can establish a connection. When attaching an usb hub you can also add more devices. U-Boot is on the SPI chip and is a version from here: https://github.com/ayufan-rock64/linux-build/releases which has some more options enabled than the default config for the board in mainline but is still based on a rather old u-boot version, hence lacking some stuff.
Is there anything I can do for further testing or debugging? Regards, Nikolai