On Monday 12 November 2012 07:30 PM, Arnd Bergmann wrote:

On Monday 12 November 2012, Vineet.Gupta1@synopsys.com wrote:

quoted

+
+config ARC_MISALIGN_ACCESS
+       bool "Emulate unaligned memory access (userspace only)"
+       default N
+       help
+         This enables misaligned 16 & 32 bit memory access from user space.
+         Use ONLY-IF-ABS-NECESSARY as it will be very slow and also can hide
+         potential bugs in code

parisc and ia64 both have the same feature, and they use sysctl to configure
it at run-time. Maybe you should pick one of the two sysctl implementations
and hook that up to your implementation as well.

Spoke too soon ! The only caveat to removing the Kconfig option is that
it will pull-in unaligned emulation code as well as the dependent
in-kernel disassembler unconditionally into the build.

Are you OK if we keep this support build time - provided that once it is
build time enabled - we have the additional runtime sysctl based
toggle-ability as you suggested.

Only one of our customers need this feature and this gives people
reasons to moan about the kernel .text size and such.

Thanks,
Vineet