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Re: JFFS2 & NAND



On Monday, 18. February 2002 10:29, David Woodhouse wrote:
> gleixner@xxxxxxx.de said:
> > Yes inside JFFS2, but who tells the NAND driver, which layout to use.
>
> Do we really need the NAND driver to be able to use more than one layout?
>
> Either we have hardware ECC which determines the layout, or the NAND driver
> implements software ECC and gets to choose. Can't the filesystem just deal
> with the ECC layout used by the NAND driver, as determined by the
> underlying hardware?
Also hardware ECC does not determine the layout. It just builds the ECC, you 
have to read it out of the CLPD and write it at a appropriate place in the 
OOB area. Same on read.  
We can use a fixed layout for every chip-type. There are 2 good reasons not 
to do that.
1. The SMC DOS-FAT oob layout is more than ugly. To press our idea of oob 
usage into this, is like you slice a bread in many small pieces to fit into 
the subdivisions of your tupperbox, instead of rearanging the contents of the 
box.

2. I don't want to put too much restrictions into the oob layout, so we would 
make it hard for somebody, who want's to implement a different filesystem 
than JFFS2.

-- 
Thomas
__________________________________________________
Thomas Gleixner, autronix automation GmbH
auf dem berg 3, d-88690 uhldingen-muehlhofen
fon: +49 7556 919891 , fax: +49 7556 919886
mail: gleixner@xxxxxxx.de">http://www.autronix.de  

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