Re: Maturity of JFFS2 + MTD NAND Flash Support?

Ricard Wanderlof
2008-09-12T14:23:23Z

On Fri, 12 Sep 2008, Ensar Gul wrote:

>> AFAIK, jffs2 doesn't handle correctly bit flip on read : it won't try to
>> copy the data on another block while the data can still be recovered
>> by ecc.
>>
>> I believe it could be a big issue for commercial product where no
>> corruption should happen.
>>
>>
>> Matthieu
>
> Is there a solution to the problem stated above yet?

I belive UBI has some form of block scrubbing to minimize the problem,
there should be more info on the mtd homepage.

> By the way, I also used JFFS2 on NAND flash as root filesystem in a
> telecom product. but the root filesystem infrequently becomes corrupt
> without any apparent reason. I`m considering to redesign the hardware
> and use an alternative device instead of NAND flash.

A while ago, there was a bug in the ECC code whereby a single-bit error in
the actual ECC bytes was not handled (i.e. corrected) correctly and
resulted in the corresponding data to be considered faulty (as if a
multiple-bit error had occurred). This was several Linux versions ago, I
don't remember the exact version.

/Ricard
--
Ricard Wolf Wanderlöf ricardw(at)axis.com
Axis Communications AB, Lund, Sweden www.axis.com
Phone +46 46 272 2016 Fax +46 46 13 61 30