Just want to document in the case people are searching for this. OpenBSD 6.6 has no problems booting of the USB and running on Ubiquiti EdgeRouter 4 (tested only USB installation as I didn't want to nuke 4GB eMMC flash storage). However, in spite of having
check_md5sum=no option in U-Boot env, bootloader is checking md5sum and automatic boot fails. The version of U-Boot shipped with my device is 2013.07. I am out of fuel tonight and have no clue how to fix the problem. Any suggestions would be appreciated. Best, Predrag P.S. I am aware of this write up https://openwrt.org/toh/ubiquiti/edgerouter.lite but I have not encountered md5sum problems on ER Lite while running OpenBSD. I will have to check U-Boot settings on working devices next time I have physical access to hardware.
