This seems backwards logic for me, as one would expect that even if the device isn't 'currently bootable' that you would still have the option to choose the device, be it 'USB device' or something similar and at least tell it to expect to boot from that location.
Basically, unless the UEFI partition exists and things are setup correctly on the device (SDcard, USB stick, USB hard drive), the BIOS will not even show the device as an option to select to boot from. I made the mistake of thinking I could just 'dd' the eMMC over to an SDcard and boot that SDcard, I was wrong, there seems to be some magic there. I my self went on a learning experience over the past day or so trying to figure out something that is essentially quite silly that I overlooked.Īny device you want to boot from MUST have a UEFI partition on the device related to the operating system you intend to boot. Here is another quick tip to help people who haven't dealt much with UEFI BIOS and the quirks of devices and booting.