If you are using embedded linux, you probably have an ip-connection to
the hw and uboot as the fw/bootlooder/bios or what you prefer to call it.
If you have an ip-connection, you can just ssh to the box and copy it to
the right place and do whatever is needed.
You usually don't update the processor, embedded board or other fw
than uboot. If you want to do that you have to check the manufacturer
... > Â Â Â I wish to every Linux fan to live this adventure.