NetBSD -current/-8 EFI CDROM boot on SuperMicro A2SDi broken

[Frank Kardel <kardel%netbsd.org@localhost>]

I just got a A2SDi-2C-HLN4F on my desk.

I have not been able to boot NetBSD-current/-8 on this device with 
following symptoms:
	1) pxeboot is loaded successfully via network and ignored
	2) loading efibootx64.efi via network work and runs - failing to access 
any file systems (bad partition).
	  dev never finishes (though it lists some disks with partitions - USB, 
simulated USB cdrom from iKVM)
        3) booting a physical CD from a USB drive also starts the EFI 
bootloader that then fails with 'bad partition' on all tried file names.

Thus 1) shows that this board does not care much about non EFI boot.
2 & 3) show that our EFI bootloader needs some care (8.99.4 and 8_BETA).

Manual transcription:
>> NetBSD/x86 EFI Bott (x86), Revision 1.0 (..) (from NetBSD 8.0_BETA)
>> Memory: 252/1971496 k
Press...
booting hd0a:netbsd - starting in 0 seconds
open betbsd: bad partition

same for netbsd.gz, onetbsd, onetbsd.gz, netbsd.old, netbsd.old.gz.

Any ideas how to proceed? Currently, I try to find out where and why 
EPART is returned.

BTW: the penguin just runs

Best regards,
  Frank