This is the mail archive of the
ecos-discuss@sourceware.org
mailing list for the eCos project.
Re: JFFS2 for NAND flash file system
- From: Stanislav Meduna <stano at meduna dot org>
- To: ecos-discuss at ecos dot sourceware dot org
- Date: Wed, 01 Jun 2011 12:54:02 +0200
- Subject: Re: [ECOS] JFFS2 for NAND flash file system
- References: <BANLkTimXMWKORK85r74wuQnF5zvuqOaXnw@mail.gmail.com> <BANLkTi=gyorSa2HKm-237g8h_VQZA6fucA@mail.gmail.com> <BANLkTi=BYZRwGJD8Spy4xbFzArTfPfjy0A@mail.gmail.com>
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
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss