On 10/5/19 10:27 pm, dufa...@hda.com wrote: > > >> On May 10, 2019, at 08:07 , Sebastian Huber >> <sebastian.hu...@embedded-brains.de >> <mailto:sebastian.hu...@embedded-brains.de>> wrote: >> >> On 10/05/2019 13:58, Gedare Bloom wrote: >>> On Tue, May 7, 2019 at 5:03 AM Peter Dufault<dufa...@hda.com >>> <mailto:dufa...@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? >> > My make pulls in those settings. I think it is best to use the same settings > that the RTEMS tests and samples unless I have a good reason to change them, > e.g., I need —whole-archive in one application in one place. > > What do you recommend? Where is an example to build from?
We do not have simple examples with documentation to support them. I receive a stream of requests about building libdl applications and all I can do is point user to the testsuite Makefile.am's. The Makefile.inc approach has a range of problems so adding documentation and examples based on it is something I do not support. The approach I would like to see happen is documented in https://devel.rtems.org/ticket/3302. You do not need to build applications with the exact same flags that the kernel uses however you need to be careful in managing what you do use. As I state in the ticket RTEMS Tools [1] and RTEMS Waf [2] both have support to filter the CFLAGS into parts so you can manage what is used when building applications. I would prefer this is formalised when exported by RTEMS rather than having to have this fragile code which does break from time to time. Chris [1] https://git.rtems.org/rtems-tools/tree/rtemstoolkit/rld-cc.cpp#n79 [2] https://git.rtems.org/rtems_waf/tree/rtems.py#n793 _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
