Re: [dpdk-dev] [PATCH] mk: add support for gdb debug info generation

[Olivier MATZ <olivier.matz@6wind.com>]

Hi Marc,

On 03/03/2015 02:27 PM, Marc Sune wrote:
>
> On 03/03/15 14:03, Bruce Richardson wrote:
>> On Tue, Mar 03, 2015 at 01:56:19PM +0100, Marc Sune wrote:
>> [...]
>> I believe that the global option of overriding the CFLAGS is already
>> sufficiently
>> covered - including being documented in programmers guide - by
>> EXTRA_CFLAGS.
>
> To be honest, I tried EXTRA_CFLAGS at some point in time (probably 1.5
> or 1.6, but maybe not stable releases) and it did not work, so I ended
> up doing it manually, and never tried again.
>
> It does work now with CFLAGS, I didn't try LDFLAGS, but it does not for
> EXTRA_CPPFLAGS apparently (unless I made some stupid mistake):
>
> marc@dpdk:~/dpdk$ git diff
> diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c
> index 4e70fa0..4a1e538 100644
> --- a/lib/librte_kni/rte_kni.c
> +++ b/lib/librte_kni/rte_kni.c
> @@ -61,6 +61,10 @@
>
>   #define KNI_MEM_CHECK(cond) do { if (cond) goto kni_fail; } while (0)
>
> +#ifdef TEST_CPPFLAGS
> +       #error TEST_CPPFLAGS defined
> +#endif
> +
>   /**
>    * KNI context
>    */
>
> marc@dpdk:~/dpdk$ export EXTRA_CPPFLAGS='-DTEST_CPPFLAGS'
> marc@dpdk:~/dpdk$ make install T=x86_64-native-linuxapp-gcc
> ...
> Build complete

The reason why it does not work is described in the documentation:

./doc/guides/prog_guide/build_app.rst:*   CPPFLAGS: The flags to use to 
provide flags to the C preprocessor (only useful when assembling .S files)
./doc/guides/prog_guide/dev_kit_build_system.rst:*   CPPFLAGS: Flags to 
use to give flags to C preprocessor (only useful when assembling .S files).
./doc/guides/prog_guide/dev_kit_build_system.rst:*   EXTRA_CPPFLAGS: The 
content of this variable is appended after CPPFLAGS when using a C 
preprocessor on assembly files.

I think your test would work with EXTRA_CFLAGS.

I don't say it's the proper behavior, but at least it's coherent with
the documentation.

Regards,
Olivier