Way to clear nand bad block table
jbe at pengutronix.de
Thu Jul 26 05:27:48 EDT 2012
Marc Reilly wrote:
> Is there a way to clear the nand bad block table?
> I'm not sure what happened, but I was playing around with barebox init and
> didn't register the nand device - then when I booted the kernel there were
> a stack of UBI errors.
> I assume this also did something to the bbt as subsequent barebox startups
> give a heap of bad block messages. Note not all blocks are bad - tested
> with nandtest and there's still some R/W going on.
> All the code I looked at seemed to indicate that once a block is marked bad
> you can't go back.
> Any ideas much appreciated.
The flash blocks which contains the "bad block table" are protected by
the "bad block table" aware MTD layer.
So, the ugly way: run a bootloader which does not use the in-flash bad block
table. Then the tables are regular blocks in the flash and can be erased.
After that run again the bad block table aware bootloader and it will
re-create the in-flash table. But be careful: In this case the generic
functions scans all blocks in the NAND to collect the bad block markers in
each NAND block's OOB. If this information is already destroyed somehow, this
solution does not help.
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