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

[Aneesh V]

On Thursday 23 February 2012 11:39 PM, Aneesh V wrote:
> On Thursday 23 February 2012 11:21 PM, Tom Rini wrote:
>> On Thu, Feb 23, 2012 at 11:19:59PM +0530, Aneesh V wrote:
>>> 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?
>>
>> Yes, it should already be at or near 0 uses.
>
> We need at least one for finally appending to the exported variable,
> right. So, looks like one += for adding '-mthumb -mthumb-interwork'
> together is better than having one each for the two options? Is that
> the logic?
>

Please ignore this question. It's clear to me now with Mike's latest 
explanation. Thanks.