Re: [bug] e100 bug: checksum mismatch on 82551ER rev10

[Auke Kok <auke-jan.h.kok@intel.com>]

Molle Bestefich wrote:
> Auke Kok wrote:
>> > Every single IP130 I've had my hands on has had an EEPROM that the
>> > Linux driver declared bad.
>>
>> that means that whoever is selling you the IP130's is consistently 
>> putting on
>> bad EEPROMs, which is *very* bad. Which vendor is that? They can fix this
>> problem for you and for *everyone* else they have sold and will sell 
>> IP130's
>> to in the future.
> 
> Nokia.
> 
> Maybe they've changed the BABA magic, or the checksum logic entirely,
> to prevent other software than their own OS from running.

in almost all cases where a bad EEPROM checksum is found on a board the vendor 
has changed settings in the EEPROM image without recalculating the checksum.

>> > I'm afraid that it's not the board that's at fault, it's the driver.
>>
>> No it is not. The NIC is supported (you can even call Intel for first 
>> line
>> support) but if your vendor put a bad EEPROM image on it then all bets 
>> are
>> off.  Intel provides the vendors with the proper tools to make valid 
>> EEPROMs,
>> the driver checks them for a very good reason.
> 
> You're completely sure that the EEPROM check is correct for this
> particular revision of this particular chip?

It's valid for every piece of network silicon that has an EEPROM ever made.

> (Do you happen to know where the EEPROM is located, by the way?

it's in the NIC itself. In your case, where you have 3 separate chips, there 
will be 3 different EEPROM images total.

>> How can you tell? Do you know if jumbo frames work correctly?  Is the 
>> device
>> properly checksumming? is flow control working properly?  These and 
>> many, many
>> more settings are determined by the EEPROM.  Seemingly it may work 
>> correctly,
>> but there is no guarantee whatsoever that it will work correctly at 
>> all if the
>> checksum is bad.  Again, you can lose data, or worse, you could 
>> corrupt memory
>> in the system causing massive failure (DMA timings, etc). Unlikely? 
>> sure, but
>> not impossible.
> 
> They've been used in production environments for years.

all the more reason to suggest that Nokia is forgetting to update the checksums :)

Cheers,

Auke