[Buildroot] [PATCH] add pre-build script

[Arnout Vandecappelle <arnout@mind.be>]

On 14/02/13 18:04, Thomas Petazzoni wrote:
> Dear Spenser Gilliland,
>
> On Thu, 14 Feb 2013 10:28:24 -0600, Spenser Gilliland wrote:
>
>> I'm not doing this with the specific implementation posted.  I'm just
>> saying it would be a nice feature to have.  Many device trees specify
>> processor/arch features and optimized cflags can be constructed from
>> this data.
>>
>> I currently do this outside of buildroot and just provide
>> BR2_TARGET_OPTIMIZATION on the make command line from the buildscripts
>> for the hardware.
>>
>> It would be nice to have buildroot completely self contained and not
>> require the software developers to download the additional hardware
>> files.
>
> Indeed, but the pre-build script approach you posted would not allow to
> customize the CFLAGS.

  Spenser didn't post it...

> The CFLAGS are part of Buildroot .config file,
> which is loaded at the time you run "make".

  Ah, right, major shortcoming if the pre-build script can't update the 
.config...

> So when your pre-build
> script gets executed by Buildroot, make has already loaded the value of
> BR2_TARGET_OPTIMIZATION.
>
> You would have to make a specific script that returns custom CFLAGS,
> and add some code in Buildroot that does:
>
> CUSTOM_CFLAGS = $(shell ./your/custom/script)

  This is a good place to do := instead of =, otherwise the script gets 
re-run for every build step...

  Regards,
  Arnout


-- 
Arnout Vandecappelle                          arnout at mind be
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