[U-Boot] NAND bad environment block handling

[Wolfgang Denk]

Dear Manfred,

In message <1231672254.3130.29.camel at mobil.alm.archives.at> you wrote:
> 
> 1. For our systems we assume, that the env-block never gets bad in
> productive use, because the env-block is never written again. So we
> reduced the problem to number of initial/factory bad blocks.

That's a pretty risky setup because  it  is  based  on  an  incorrect
assumption  - on NAND, block become not only bad when being erased or
written to, but also after a certain number  of  read  operations  is
exceeded.  Yes, there is a maximum number of reads per block on NAND!
People like to ignore that... See for example  the  Micron  Technical
Note   "Design   and  Use  Considerations  for  NAND  Flash  Memory",
http://download.micron.com/pdf/technotes/nand/tn2917.pdf

Time to look into UBI, me thinks.

Best regards,

Wolfgang Denk

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