[PATCH v2] ARM: Define wfi() macro for v6 processors

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Tue, Feb 08, 2011 at 04:17:58PM +0100, Arnd Bergmann wrote:
> On Tuesday 08 February 2011, Dave Martin wrote:
> > CFLAGS_cpu_specific_object.o        += -march=armv7-a
> > 
> > Whether it's safe to do it depends on whether code from that file
> > could ever get run on other processors.  I'm not so sure of the answer
> > to that..., but perhaps someone else has a better idea.
> 
> We already do this a lot from arch/arm/mm/Makefile, and those
> files are typically just one function per file, so they can easily
> be proven to be safe that way.

No, we do that with assembly files.  It doesn't work soo well with
C files as we really don't want GCC itself to generate v7 instructions
unless we explicitly ask for them.

The other issue here is that somtimes generating code with different
-march options leads to the linker refusing to link them together...

Unfortunately, ARM toolchains have been developed with the assumption
that you're only building a program for one specific CPU, not
targetting multiple CPUs.