JFFS2 question

JFFS2 question

[Vahid Fereydunkolahi]

Hi,
 If on the JFFS2 Erase block 0 (jeb0) I wrote pages
p0, p1, p2, and p3, and then I updated these pages on
jeb1 with p0', p1', p2'  and on the jeb2 with p3',
what would happen if the jeb1 goes bad (When I read
the data back, is it goint to be p0, p1, p2, p3')?


Regards,
--vahid


		
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Re: JFFS2 question

[Josh Boyer]

On 11/9/05, Vahid Fereydunkolahi <fereydunk@yahoo.com> wrote:
> Hi,
>  If on the JFFS2 Erase block 0 (jeb0) I wrote pages
> p0, p1, p2, and p3, and then I updated these pages on
> jeb1 with p0', p1', p2'  and on the jeb2 with p3',
> what would happen if the jeb1 goes bad (When I read
> the data back, is it goint to be p0, p1, p2, p3')?

Can you define what "goes bad" means?  If you're using NAND flash and
you get an ECC error, it can be a soft error and doesn't necessarily
mean the block itself is bad.  See the "How does JFFS2 handle a block
going bad in NAND flash" topic here:

http://linux-mtd.infradead.org/faq/jffs2.html

If you mean something else it depends which nodes are effected.  Each
node (p0', p1', p2'), has it's own CRC.  If any/all of those are bad,
you'll see an error message displayed and the previous node will be
used.

Hope that helps.

josh