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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: jffs2 and unaligned access
Date: Wed, 7 May 2008 22:42:28 +0200
To: David Woodhouse <dwmw2@infradead.org>
Cc: linuxppc-dev@ozlabs.org, Sascha Hauer <s.hauer@pengutronix.de>,
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>> memcpy_from/to_io() use word aligned accesses on the io side of 
>> memory.
>> The MPC5200 local plus bus where our flashes are connected does not
>> allow unaligned accesses, so we have to use the io versions of memcpy.
>
> But this region of flash is marked as suitable for execute-in-place,
> otherwise the point() function wouldn't be working to give a direct
> pointer to it. It sounds like we shouldn't be allowing that.
>
> Which in turn means that perhaps we should have a property in the
> corresponding node in the device-tree which indicates that it's not
> suitable for direct access?

This isn't usually a property of the flash device, but of the various
buses/controllers above the flash device.  The device tree should mimic
reality (and it does, it just seems the kernel doesn't use this 
information
yet?)


Segher