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

Dave Martin dave.martin at linaro.org
Wed Jul 27 10:32:34 EDT 2011


On Wed, Jul 27, 2011 at 10:10:46AM -0400, Nicolas Pitre wrote:
> 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.

Can I take that as an Ack?

Cheers
---Dave



More information about the linux-arm-kernel mailing list