[U-Boot] [PATCH v2 3/5] ARM: enable Thumb build

[Tom Rini]

On Thu, Feb 23, 2012 at 10:58:36PM +0530, Aneesh V wrote:
> On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote:
> >On Thursday 23 February 2012 08:39:43 Aneesh V wrote:
> >>--- a/arch/arm/config.mk
> >>+++ b/arch/arm/config.mk
> >>
> >>-# Explicitly specifiy 32-bit ARM ISA since toolchain default can be
> >>-mthumb: +# Choose between ARM/Thumb instruction sets
> >>+ifeq ($(CONFIG_SYS_THUMB_BUILD),y)
> >>+PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\
> >>+			$(call cc-option,-marm,)\
> >>+			$(call cc-option,-mno-thumb-interwork,)\
> >>+		)
> >>+else
> >>  PF_CPPFLAGS_ARM := $(call cc-option,-marm,)
> >>+PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,)
> >
> >this 2nd part is no good.  "+=" is not the same thing as ":=".
> 
> I don't understand the difference. '+=' is done after ':=' right?

'+=' is evaluated every file we build, ':=' is evaluated once.  We use
the latter to keep build times down.

-- 
Tom