As far as I know (I used OpenBSD some 15 years ago for a while, and now is been some months, so don't trust me too much) there is no system console driver for arm. You have to use a serial console (there are very cheap CH341 usb to ttl ones) to see the output from the kernel at boot time. If you don't have one at hand, you can take advantage of the efifb support of wscons in two ways:
Using X11: enable xenodm on rc.conf.local. Using getty: Put something like this in /etc/ttys ttyC0 "/usr/libexec/getty std.9600" vt220 on secure Ask the list for the best argument to getty, I tried std.9600 and just worked. What you are seeing is the kernel loading and using the first serial console as the system one. I bet it is alive, just make one of the changes above and wait a little. By the picture of the screen it seems that you are using the firmware of the board. I don't know if that could be a problem. Better use u-boot from ports. Regards, adr.
