[Soekris] BIOS setting stored in NatSemi EEPROM?

[Dev Kumar]

Rob Flickenger wrote:

> On Aug 15, 2004, at 11:01 PM, John Zhuge wrote:
>
>> Once I changed the EEPROM offset 16 (17th word) from its default value
>> 0xFFFF, Soekris BIOS (v1.23a) starts to get into PXE Boot no matter
>> whether my CompactFlash has a bootable system or not. I have seen it on
>> net4521 and net4801.
>
>
> Does it PXE and fail if no server is present, or does it eventually 
> boot the CF?
>
> Is this the only way to make it PXE on every boot?
>
> Cheers,
>
> --Rob


It will try to PXE boot every time, even when there is a valid CF in the 
slot, and it will eventually timeout and boot the CF if there is no 
server present.
If you change the value in this 17th word back to all 0xFFFF, then it 
boots as expected: from the CF if present, from PXE if not.
I think you can make it PXE boot by default normally just with a BIOS 
setting.

It seems as though this EEPROM setting is either -

1) changing the behavior of the NatSemi NIC so the BIOS thinks it is the 
default bootable device
 or
2) changing the behavior of the BIOS directly to try to PXE boot by 
default - does the BIOS read the NIC EEPROM directly?

This behavior is replicated on 1.24, we have not tried it on 1.26 
because the PXE boot stuff seems different and broken there.

The bottom line is that we are trying to store some simple ID info on 
the unused parts of the EEPROM, at least according to the NatSemi 
datasheet, and then the board behavior changes. Any ideas on what parts 
of the EEPROM are truly reserved and used, and which are really free for 
use, is appreciated.

Thanks,

Dev