Re: [ECOS] JFFS2 for NAND flash file system

[Stanislav Meduna <stano at meduna dot org>]

On 01.06.2011 11:23, Paul MAILLET wrote:

> For me it is clear that the FS has nothing to do with all the NAND
> drawbacks, it's the job of the NAND support layer, isn't it?

If I understand it correctly, unfotunately that's not the case -
the NAND layer does not implement an abstraction of linear
error-free blocks, rotated and refreshed according to the
hardware needs. The filesystem still needs to know what
it is allowed to do - see e.g.
http://www.kernel.org/doc/htmldocs/mtdnand.html

  Filesystems must be aware of the NAND pecularities
  and restrictions. One major restrictions of NAND Flash
  is, that you cannot write as often as you want to a page.
  The consecutive writes to a page, before erasing it again,
  are restricted to 1-3 writes, depending on
  the manufacturers specifications. This applies similar
  to the spare area.

My question is: would it be possible/desirable to implement
an abstraction layer similar to e.g. a controller in
a SD-Card or a SSD flash drive? Then it would be possible
to use just about any fs, including FAT and similar beasts.

Regards
-- 
                                  Stano

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