libbsd configure removes -D flags from CFLAGS of pkg-config

[Chris Johns]

On 14/9/20 3:06 pm, Sebastian Huber wrote:
> On 14/09/2020 01:46, Chris Johns wrote:
>> On 13/9/20 3:46 am, Sebastian Huber wrote:
>>> Hello,
>>>
>>> I can't build the libbsd for powerpc/beatnik:
>>>
>>> ---------------------------------------------
>>> Compiler version (powerpc-rtems6-gcc)
>>> 10.2.1 20200904 (RTEMS 6, RSB 47f32b8b1a597b5ed3475722bdc155249ef51115, Newlib
>>> a0d7982)
>>> Opening and load pkgconfig:
>>> /ramdisk/git-rtems-6/build/install/lib/pkgconfig/powerpc-rtems6-beatnik.pc
>>> -----------------------------------------
>>> CFLAGS ->
>>>     -qrtems -B/ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib
>>> -D__ppc_generic -mcpu=7400
>>> LDFLAGS ->
>>> pkconfig warning: Label not found: LDFLAGS
>>>
>>> LIB ->
>>> pkconfig warning: Label not found: LIB
>>>
>>> ---------------------------------------------
>>> Checking for a valid RTEMS BSP installation
>>> ==>
>>> #include <rtems.h>
>>> void Init(rtems_task_argument arg) { (void)arg; }
>>> #define CONFIGURE_APPLICATION_DOES_NOT_NEED_CLOCK_DRIVER
>>> #define CONFIGURE_MAXIMUM_TASKS 1
>>> #define CONFIGURE_RTEMS_INIT_TASKS_TABLE
>>> #define CONFIGURE_INIT
>>> #include <rtems/confdefs.h>
>>> <==
>>> [1/2] Compiling build/.conf_check_261484d99ea5da27480d47dee9a30c04/test.c
>>>
>>> ['/build/rtems/6/bin/powerpc-rtems6-gcc', '-qrtems',
>>> '-B/ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib', '-mcpu=7400',
>>> '-MMD', '../test.c', '-c',
>>> '-o/ramdisk/git-rtems-libbsd/build/.conf_check_261484d99ea5da27480d47dee9a30c04/testbuild/test.c.1.o']
>>>
>>>
>>> err: In file included from
>>> /ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib/include/libcpu/powerpc-utility.h:46,
>>>
>>>
>>>                   from
>>> /ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib/include/bsp/vectors.h:40,
>>>
>>>
>>>                   from
>>> /ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib/include/bsp.h:45,
>>>                   from
>>> /ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib/include/rtems/confdefs/bsp.h:53,
>>>
>>>
>>>                   from
>>> /ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib/include/rtems/confdefs/extensions.h:45,
>>>
>>>
>>>                   from
>>> /ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib/include/rtems/confdefs.h:67,
>>>
>>>
>>>                   from ../test.c:7:
>>> /ramdisk/git-rtems-6/build/install/powerpc-rtems6/beatnik/lib/include/rtems/powerpc/powerpc.h:289:2:
>>>
>>> error: #error "Unsupported CPU Model"
>>>    289 | #error "Unsupported CPU Model"
>>>        |  ^~~~~
>>>
>>> I haven't figured out why the "-D__ppc_generic" is removed from the CFLAGS.
>>
>> There are multiple places filtering happens. It could be rtems_waf ...
>>
>> https://git.rtems.org/rtems_waf/tree/rtems.py#n840
>>
>> of pkgconfig in the RSB ...
>>
>> https://git.rtems.org/rtems-source-builder/tree/rtems/config/rtems-bsp.cfg#n40
>> https://git.rtems.org/rtems-source-builder/tree/source-builder/sb/config.py#n512
>>
>> Exporting of internal build flags by RTEMS to applications needs to be consider
>> a bug. This happens in a small number of cases like this one but the effort and
>> complexity involved in managing these cases outside of Makefile.inc is growing.
>>
>> I am reluctant to support adding exceptions to the filtering of flags to manage
>> things like this because it is a slippery slope and fragile. The hack at the
>> moment is to take the flags and remove the warning ones. In rtems_waf the
>> filtering goes further to group the flags to isolate machine flags so the ABI
>> can be cleanly exported to the 3rd party libraries and applications.
> 
> The goal should be to export the information in the new build system so that we
> don't have to filter it.

Yes. We should only export the machine flags in pkgconfig's CFLAGS.

We can export other things from a BSP but they need to be plgconfig variables..
An example would be mkimage arguments if the BSP can be booted by u-boot.

> 
>>
>> I think using a command line -Dsomething to control a machine configuration
>> outside of the RTEMS build arena is fragile. Can this be added to the powerpc's
>> bspopts.h as a #define for this BSP?
> 
> It is just something that came up during the testing of the new build system.

Ah OK.

> I think this define can go away at some point in time.

That would be great.

Chris