@JosDuchIt
AFAIK other users that upgraded UBoot SAM460ex had same problem.
Looking and waht the latest UBoot (
http://www.acube-systems.biz/index.php?page=news&id=134)
...
- removed 2 GB limit for USB sticks
...
IMPORTANT NOTICE: users with an USB A-Eon AmigaOne keyboard may experience a problem with too many repeated keys, in this case, if possible, use another USB keyboard, or wait for a new update.
We had several feedback saying that Logitech keyboards K120 work perfectly with Uboot (also MK220 are reported to work).
So for one side is that maybe SUB keyboard doesn't wortk under UBoot (but no problems under AOS4) and there a fixes/features the are good to update to such UBoot.
I'm using a Microsft Wired Keyboard 200 and no problems under UBoot/AmigaOS4