On Thu, Oct 11, 2007 at 10:35:55AM -0400, Ian McDonnell wrote:
> Ben,
>
> On Thursday 11 October 2007 07:25, Ben Dooks wrote:
> > I'm working on upgrading a client's kernel from 2.6.10 to
> > 2.6.22. They are using yaffs to store their configuration
> > data.
> >
> > When I start the 2.6.22 kernel, I get a number of the
> > following: **>> yaffs chunk 32 was not erased
> >
> > If I run 2.6.10 after writing the files from 2.6.22 I get
> > blocks with ECC errors in them, and the files get corrupted.
>
> The problem is with a change to MTD -- MTD's NAND interface had
> an overhaul between 2.6.17 and mid-late 2.6.18. MTD's default
> layout of oob data in the NAND page's spare area changed. This
> means that yaffs' tag metadata gets scrambled when you jump
> between versions of MTD. There are ways to fix this, you can
> supply MTD with your own layout policy. Rumage through the mail
> archive to find some discussion on the topic.
> http://aleph1.co.uk/lurker/list/yaffs.en.html
I didn't find anything relevant to this. I have found one problem,
if CONFIG_YAFFS_DOES_ECC is set, and the mtd driver has an ECC
method, then it seems to be using the mtd hardware ECC code during
reads. The Kconfig help text seems to imply this should override
anything NAND is up to?
Even with the hardware ECC disabled, nipping between the two
kernels is still giving:
yaffs_ECCCorrect: READ ff,ff,bf WANT ff,ff,ff, DIFF 00,00,40
The diff value is _always_ 00,00,40 whatever the ECC being read.
--
Ben
Q: What's a light-year?
A: One-third less calories than a regular year.
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