[Buildroot] using BR2 variables to find a specific header file

[Sylvain Raybaud]

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Mike, Samuel, all,

On 13/10/2014 21:42, Samuel Martin wrote:
> Hi Sylvain,
> 
> On Mon, Oct 13, 2014 at 7:10 PM, Sylvain Raybaud 
> <sylvain.raybaud at green-communications.fr> wrote:
[...]
>> During cross-compile these tests cannot be run therefore the
>> package expects -DSTACK_DIRECTION=+/-1 to be passed to cmake. Of
>> course you cannot do it in buildroot.
> 
> Why do you say that? Of course, Buildroot does support adding cmake
> configure options [1]. You can also check some cmake-based packages
> already integrated (e.g.: [2]).

I mean I can pass arguments to cmake but if I hardcode a value I break
compatibility with any platform that would require the other value.
However...

> 
> If you know beforehand how grow the stack, I would suggest to set
> it in the *_CONF_OPTS variables. This may depends on the target
> architecture.
> 
>> It seems to be possible to access this information in another
>> way since STACK_GROWS_DOWNWARD is defined in some headers.
[...]
> 
> This does not look right :-/ because: - it search in something not
> in the sysroot; - it is only valid when using the
> buildroot-toolchain backend.
> 
> Indeed, it seems the STACK_GROWS_DOWNWARD definition is only
> available in the compiler sources, not in the preprocessor output
> for the target :-/
> 
>> [...]
> 
> Instead of checking the compiler sources, I prefer you set the
> stack growing direction through the CMake args.
> 
> Regards,

Mark's reply and yours strongly suggest that it's a better idea to
hardcode the correct value. I shall do so!

Thanks a lot!

Cheers,

- -- 
Sylvain Raybaud
www.green-communications.fr
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