[Differential] [Commented On] D2017: Allow to disable alignment faults in the kernel configuration file

[zbb (Zbigniew Bodek)]

zbb added a comment.

**Jakub Palider wrote:**
(NOTE)
Unaligned access is controlled by two bits in SCTRL register on ARMv6+
architectures, the U bit for unaligned support (on ARMv7+ always set)
and the A bit. This patch refers to bit A only, so we can just tell the
processor not to raise exception when such situation happens, but rather
silently perform additional fetches etc. I believe that has nothing to
do with userspace, unless someone aims at fine-tuning their application
and wants notification on unaligned accesses just to eventually get rid
of them, but that is another story. In kernel we do have unaligned
accesses, so extra handling results in unnecessary overhead and
performance degradation.

REVISION DETAIL
  https://reviews.freebsd.org/D2017

To: zbb, ian, andrew, imp
Cc: freebsd-arm