On Sat, 23 Nov 2002 04:38, Thomas Gleixner wrote:
> On Friday 22 November 2002 11:00, Nick Bane wrote:
> > 1) Patch the nand.c in mtd to ignore the ecc calculations if
> > NAND_ECC_NONE is selected.
> > 3) Do ones own nand interface and make sure that NAND_ECC_NONE is
> > asserted (be aware that this makes the rest of the chip unsuitable for
> > CRAMFS/JFFS2)
>
> Maybe it would be more conveniant to use the latest nand-code from
> mtd-cvs,. where a lot of speedups were done and the selection of ECC is
> possible through the filesystem driver, as I posted on 9-25-02 on this
> list. The actual JFFS2 code supports this new behaviour and it should be no
> big deal to modify yaffs to use it too. So you can use both on one system.
>
> This would surely increase the chance to get it into the kernel code
> sometime.

Thomas,

I have sort-of been meaning to work with the new mtd for a while but never 
seem to get around to it. This also works in with the stuff that Christian 
Gan did to get his hardware ECC working.

At some stage I intend to (or someone else can) re-compartmentalise  the 
yaffs bottom end to support more flexible placement of ECC.

One thing I have realised (and this might be a Good Thing for mtd too) is 
that some options are best not compiled in, but run-time selected. With 
YAFFS2, I intend to allow both YAFFS1 and YAFFS2 in a single system with 
YAFFS1 or YAFFS2 being runtime selected (as well as other attributes such as 
internal caching, chunk size etc which are now compile time selected). The 
reason for this is that a smaller partition (eg boot partition) might be more 
suited to YAFFS1 and a larger partition to YAFFS2.

In mtd, for example, is it perfectly reasonable to think that an mtd in a 
single system might need to run JFFS, YAFFS and some other fs 
(??FAT/SmartMedia??) all with different feature requirements (eg. ECC, 
placement of ECC data). Would it not be better to control these on a 
per-parftition basis?

-- Charles


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