[Yaffs-archive] Re: yaffs: serious error in yaffs guts

[Charles Manning]

Nick

Thanx for pointing these out. I will fix them ASAP.

The impact is only on those people using Linux with NANDECC and is benign to 
WinCE and YAFFS direct.

-- Charles

On Fri, 28 Feb 2003 05:31, Nick Bane wrote:
> Charles
>
> A couple of bugs. One serious, one minor.
>
> in yaffs_ReadChunkFromNAND when dev->useNANDECC is true, it is assumed that
> readChunkFromNAND fills in the two ecc result integers on the end of the
> oob data.
> These are then tested to see if there has been and ecc read fail/correction
> by the mtd layer.
>
> The problem with this is that readChunkFromNAND never actually passes the
> ecc correction data back but leaves it in a local variable tmpSpare and
> only copies YAFFS_BYTES_PER_SPARE from it.
>
> The serious consequence of this is that all chunk reads are then flagged as
> failures and their blocks are marked as needing retiring once the data is
> erased so yaffs nand becomes effectively write-once. The really serious
> consequence of this is that one cannot now distinguish between
> yaffs_retired_blocks and nand_factory_bad_blocks so one has to
> speculatively erase the entire device losing the factory erase data (which
> seems to be zero on devices I have seen). Shouldn't we use a value other
> than 0 for yaffs to mark the block as bad (with more than two zero bits) so
> they can be distinguished?
>
> The other bug is in testing the ecc correction results in
> yaffs_ReadChunkFromNAND.
> if(nspare.eccres2 || nspare.eccres2)
> Clearly one of them should be eccres1
>
> Nick
>
> -------------------------------------------
> Nick Bane
> Cambridge, UK.
> +44(0)1954 719270
>
>
>
>
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