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SubjectRe: ARM unaligned MMIO access with attribute((packed))
From: Måns Rullgård <>
Date: Wed, 02 Feb 2011 23:08:01 +0000

> David Miller <> writes:
>> From: Russell King - ARM Linux <>
>> Date: Wed, 2 Feb 2011 16:37:02 +0000
>>> 1. there's no way to tell GCC that the inline assembly is a load
>>> instruction and therefore it needs to schedule the following
>>> instructions appropriately.
>> Just add a dummy '"m" (pointer)' asm input argument to the inline asm
>> statement. Just make sure "typeof(pointer)" has a size matching the
>> size of the load your are performing.
> That should be "m"(*pointer).

Right, thanks for the correction.

>> But you really need that memory clobber there whether you like it or
>> not, see above.
> I don't know of any device where the side-effects are not explicitly
> indicated by other means in the code triggering them, so it probably
> is safe without the clobber as Russel says.

You're probably right.
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