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

Dave,

-----Original Message-----
From: Dave Martin [mailto:dave.martin at linaro.org]
Sent: Tuesday, February 08, 2011 8:16 PM
To: Arnd Bergmann
Cc: linux-arm-kernel at lists.infradead.org; Russell King - ARM Linux;
Nicolas Pitre; Tony Lindgren; Santosh Shilimkar; linux-
omap at vger.kernel.org; Jean Pihet
Subject: Re: [PATCH v2] ARM: Define wfi() macro for v6 processors

[....]

For (2), I think the best approach is to use the actual "wfi"
instruction and build the affected files with the appropriate -
march=
flag (omap already does that) - since those CPU-specific files
should
by definition never be run if running on another CPU.  We only
support
new enough tools these days that this should be supported; so "wfi"
should be preferable to ".long 0xdeadbeef" - otherwise we need lots
of
#ifdef CONFIG_THUMB2_KERNEL, or a macro.  If we have a macro, it
would
be better for that to be generically implemented somewhere, becasue
the requirements are the same for every BSP supporting v7.

I don't like the practice of pre-assembling bits of code with .long,
in order to allow a file to be built with wrong -march= flags, and I
would favour migrating away from this where possible ... but I
accept
it's a pragmatic solution to a problem for which gcc/binutils
provide
no good alternative.

How about C files where 'wfi' used using inline assembly.
Can we also specify the " -march=" for the C files as well ?

Regards,
Santosh