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Subject: Re: JFFS2 on Lite5200
From: Artem Bityutskiy <dedekind@infradead.org>
To: Andrey Volkov <avolkov@varma-el.com>
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Date: Tue, 17 Oct 2006 17:18:44 +0300
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Cc: Andrea Galbusera <andrea.galbusera@teamware.it>,
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On Tue, 2006-10-17 at 17:20 +0400, Andrey Volkov wrote:
> Andrea, check ml archive, I already sent patch half-year ago
> (http://ozlabs.org/pipermail/linuxppc-embedded/2006-April/022566.html)
> Problem is in alignment/memcpy: JFFS2 code assumed that memory at
> unaligned addresses could be touched, but access to an external MMIO
> on MPC5200 _must_ be aligned (i.e. you could not read u32 from odd addres=
s).
>=20
> P.S. Artem, I repeat, I sent this patch _HALF_YEAR_AGO_
> how about to fix scan.c?

Just talked to David. Please, find the result of our discussion in my
edition below.

Strictly speaking, JFFS2 *does not* do anything wrong, so it should not
be fixed. Indeed, JFFS2 does have full right to use memcpy() for that.

The question is: does memcpy() make sense for flash adresses at your
board? Is it a valid operation for flash addresses at your board?

If the answer is yes - then please fix memcpy() for your platform.

If no - then please, do not pretend that your flash may be treated as
memory and fix your platform MTD driver. Namely, set point()/unpoint()
to NULL in your mapping driver - JFFS2 should work then.

--=20
Best regards,
Artem Bityutskiy (=D0=91=D0=B8=D1=82=D1=8E=D1=86=D0=BA=D0=B8=D0=B9 =D0=90=
=D1=80=D1=82=D1=91=D0=BC)