RE: [ECOS] Re: RE : JFFS2 for NAND flash file system

[Lambrecht Jürgen <J dot Lambrecht at TELEVIC dot com>]

> -----Original Message-----
> From: ecos-discuss-owner@ecos.sourceware.org [mailto:ecos-discuss-
> owner@ecos.sourceware.org] On Behalf Of Ross Younger
> Sent: dinsdag 31 mei 2011 17:42
> To: ecos-discuss@ecos.sourceware.org
> Subject: Re: [ECOS] Re: RE : JFFS2 for NAND flash file system
> 
> * Paul MAILLET <paulmaillet37@gmail.com> wrote:
> > As my target use NAND
> > flash and JFFS2 doesn't support it, I would like to know if it is
> > really problematic or dangerous or anything that I should be aware of
> > when using it on NAND flash device.
> 
> Running a non-NAND-aware filesystem on NAND is a very bad idea.
> 
> On NAND parts it is mandatory to implement an error correcting code
> (ECC),
> either in software, or in hardware if your board's memory controller
> supports it. Any given NAND part's datasheet should contain details

[snip]

Mark that 1-bit ECC can be calculated in SW (on our ARM9 it works), but not the current 4b ECC (it will be too slow). Then you really need HW support. And soon 8b ECC will be required! So check your micro-controller's NAND flash driver!
Our Micron part was made obsolete, but with pin compatible replacements, but with 4b instead of 1b ECC.
OK, Micron has on-die ECC, but only for the current parts (obsolete in a few years?), not for the future parts with 8b ECC, and not for the biggest parts.

Regards,
Jürgen

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