NAND OOB data.

Mon Jun 20 13:53:41 EDT 2011

> -----Original Message-----
> From: Atlant Schmidt [mailto:aschmidt at]
> Sent: Monday, June 20, 2011 6:14 AM
> To: ANDY KENNEDY; linux-mtd at
> Subject: RE: NAND OOB data.
> Andy:
>   If you don't have the old bad block information saved
>   away somewhere (a bad block table, a scrap of paper,
>   etc.), then you *CAN'T* completely recover from this
>   situation; the original bad block data for that chip
>   is probably irretrievably lost.*

All the other boards apparently are all good (is that normal?), but,
I'm not worried about the NAND having KNOWN bad blocks as this board
is supposed to be mine.

>   You can mark all the blocks as "good", of course, and
>   then exercise the chip a bit, marking bad blocks as you
>   go. You'll probably never achieve the same depth of
>   testing that the factory was able to achieve using
>   voltage, temperature, and timing margining, of course,
>   but the results may be "good enough".
>                           Atlant

Okay, so how do I (without the luxury of u-boot), in user or
kernel space, wipe the OOB data?  I'm looking at the code for
u-boot nand_erase_nand right now.  I mean, I'm not above writing
an userspace app that will do kernel level work for me.  I'm okay
with using /dev/mem and screwing with stuff.  Am I on the right
track?  I mean, I hate to go down this road if I'm just heading
for a dead-end.


> * A few chip designs apparently blow fuses for the
>   factory bad sectors and these blown fuses prevent
>   you from ever writing the OOB bits to the state
>   that would indicate a good block. For chips of
>   these designs, you can fully recover the factory
>   bad block data.
> -----Original Message-----
> From: linux-mtd-bounces at [mailto:linux-mtd-
> bounces at] On Behalf Of ANDY KENNEDY
> Sent: Friday, June 17, 2011 18:09
> To: linux-mtd at
> Subject: NAND OOB data.
> I have overwritten my OOB data, to the point where all blocks are
> seen
> as bad.  What do I do to recover from this?
> Thanks,
> Andy
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