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Date: Sat, 14 Apr 2012 14:11:05 +0200
From: Ivan Djelic <ivan.djelic@parrot.com>
To: Artem Bityutskiy <dedekind1@gmail.com>
Subject: Re: UBI/UBIFS issue: corrupt empty space => switched to read-only mode
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 Matteo Mattei <matteo.mattei@gmail.com>
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On Fri, Apr 13, 2012 at 04:20:45PM +0100, Artem Bityutskiy wrote:
> > > On Fri, 2012-03-16 at 17:14 +0100, Matteo Mattei wrote:
> > > > Hi guys,
> > > >=20
> > > > I am working hard on UBIFS to make it works on 2.6.32 and OMAP3530.
> > > >=20
> > > > I already posted some requests to TI forum but I have no answers up=
 to now:
> > > > http://e2e.ti.com/support/embedded/linux/f/354/t/171839.aspx#627875

Hello Matteo,

I have been using a very similar setup (2.6.32 + OMAP3630), and I added BCH=
 support
(8-bit correction) to the mtd omap2 driver, using the BCH library (not TI i=
mplementation).
My patch corrects bitflips on empty space (erased pages), so that UBIFS doe=
s not choke on corrupted empty space.

I posted a patch a while ago, albeit for a more recent kernel version:
http://lists.infradead.org/pipermail/linux-mtd/2011-October/038207.html
bit I did not get much feedback from TI maintainers.

If you have some trouble backporting this patch to your kernel, let me know=
, I may
have an old 2.6.32 version of the patch somewhere on my hdd :).

BR,
--
Ivan

> >=20
> > Hi Aartem,
> > I have some updates (also a BCH fix) as reported here:
> > http://e2e.ti.com/support/embedded/linux/f/354/t/171839.aspx
> >=20
> > Anyway the read-only mounting persists.
> > I have errors also at run time (without power cuts) simply performing v=
ery=20
> > frequent and stressful reading/writing operations (using dd and md5sum =
with 8=20
> > parallel processes).
>=20
> Does BCH in your tree protects the free space? CCing Ivan, just in case.
> Preserving more than usual of the context for him.
>=20
> >=20
> > At this point I am wondering:
> > 1- Is possibile that the "unstable bits" issue happens also during run-=
time=20
> > simply reading and writing?
>=20
> Not as far as I know.
>=20
> > 2- How can I do to tolerate bit-flips in the empty space?