[fm-discuss] AMD Chipkill Syndrome related query

[Srihari.Venkatesan at Sun.COM]

Thanks Gavin,

  another basic question please..

  ECC bits are used to correct/detect data bits. How does the ECC 
mechanism work
  for the ECC bits themselves, when they are affected?

  i.e., is there a second level protection for the meta-data(ECC bits) 
themselves..? is there a
  short table/mapping maintained for an Address-Data and its recent ECC 
code and then compared
  on a read, or do the ECC bits themselves get stored in DRAMs and are 
treated as
  regular data, during ECC execution?


Thank you
Srihari


Gavin Maltby wrote:

> On 01/23/08 04:47, Srihari.Venkatesan at Sun.COM wrote:
>
>> Hi,
>>
>>   On AMD (with Chipkill ECC support), if there is a syndrome(CE) that 
>> maps to
>>   a symbol 22h - which according to the doc - " the symbols 22h-23h 
>> maps to
>>   ECC check bits for data bits from 64-127 " -  does this mean that 
>> the ECC
>>   check bits themselves are in trouble/affected  ?
>>
>>   please advise..
>
>
> Yes, that is correct.
>
> Gavin
>
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