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

Aneesh V
2012-02-23T17:49:59Z

On Thursday 23 February 2012 11:04 PM, Tom Rini wrote:
> 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.
>

Ok. so, are we trying to reduce the number of "+=", right?

Thanks for clarifying.

br,
Aneesh