Conditionalize make behavior e.g. disable --gc-sections

[Sebastian Huber]

On 10/05/2019 13:58, Gedare Bloom wrote:
> On Tue, May 7, 2019 at 5:03 AM Peter Dufault<dufault at hda.com>  wrote:
>> What is best practice to change build behavior?  e.g. I need to use --whole-archive/--no-whole-archive in one place but --gc-sections breaks it and that's turned on for the BSP (xilinx_zynq_a9_qemu).
>>
>> I’ve done this in the .cfg files for the BSP:
>>
>> ifneq ($(RTEMS_GC_SECTIONS_DISABLE),1)
>> LDFLAGS_GC_SECTIONS_DISABLE = -Wl,--gc-sections
>> endif
>>
>> (...)
>>
>> LDFLAGS = $(LDFLAGS_GC_SECTIONS_DISABLE)
>>
>> and then I set RTEMS_GC_SECTIONS_DISABLE=1 in the one Makefile where I need it.  I don’t see similar patterns, is this the way to do it?
>>
> Historically a new BSP variant has been introduced when there needs to
> be a change at this .cfg level. But, I could see a rationale to
> include this kind of switching behavior at a higher level. Someone
> might consider how to integrate it into our configure.ac/Makefile.am
> black magic, but that is beyond me:).
>
> An alternative approach that may work from what you propose is to use
> following in the xilinx zynq .cfg file:
> LDFLAGS ?= -Wl, --gc-sections
> then, you can provide own LDFLAGS = -Wl on your make command line or
> in your Makefile, I think that would work bit more elegant

Nobody forces you to use -Wl, --gc-sections to link your application. 
For the RTEMS tests and samples this shouldn't be an issue?

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber at embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.