gluebi and flash file systems using the OOB
Shmulik Ladkani
shmulik.ladkani at gmail.com
Wed Jul 25 07:26:02 EDT 2012
Hi Diego,
On Wed, 25 Jul 2012 12:33:53 +0200 Diego COSTE <diego.coste at st.com> wrote:
> But we also have to use alternate flash file systems (JFFS2, YAFFS2).
> Unfortunately these file systems use the OOB and therefore can't
> directly work with the HW we use.
You should consider using UBIFS if possible.
> Then I saw that there is gluebi that re-exports a MTD, and that it is
> possible to use JFFS2 on top of it.
Gluebi exports a virtual MTD for each UBI volume.
This MTD's type is MTD_UBIVOLUME.
It is not a NAND MTD (MTD_NANDFLASH) - it does not have bad blocks,
pages, and oob part. It "resembles" NOR flash.
> Does gluebi provide an OOB emulation so that we can use *any* flash file
> system that uses the OOB ?
No.
Note JFFS2 works on top of NOR MTDs (and as such, doesn't use OOB).
So it *should* work on an MTD_UBIVOLUME as well.
However if jffs2 is mounted on MTD_NANDFLASH, it utilizes the OOB.
I remember reading something about inband tags for yaffs2.
Don't know the exact status of this; I think you should take a look.
Regards
Shmulik
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