[PATCH v2] ARM: alignment: Prevent ignoring of faults with ARMv6 unaligned access model

[Nicolas Pitre]

On Wed, 27 Jul 2011, Dave Martin wrote:

> On Tue, Jul 26, 2011 at 05:28:57PM -0400, Nicolas Pitre wrote:
> > Why not clearing the U bit as well as the A bit to preserve consistency 
> > with the pre ARMv6 behavior?
> 
> The old unaligned access behaviour is deprecated in ARMv6 (I believe)
> and is not supported at all in ARMv7 -- i.e., you can't turn the U bit
> off.  So this would be an additional special behaviour for ARMv6 only.
> 
> I'm not sure that introducing yet another behaviour is useful here;
> anyone with legacy userspace software relying on the old unaligned
> access model presumably fixed it years ago.
> 
> Really, the patch was just intended resolve the inconsistency where
> the policy the kernel enforces for the alignment fixup mode on bootup
> is not enforced at run-time.

OK, that makes sense then.


Nicolas