[Xenomai] Won`t build on new Debian Stable

Philippe Gerum rpm at xenomai.org
Thu Oct 19 19:17:27 CEST 2017


On 10/19/2017 06:55 PM, Henning Schild wrote:
> On Thu, 19 Oct 2017 12:03:33 +0200
> Philippe Gerum <rpm at xenomai.org> wrote:
> 
>> On 10/13/2017 01:36 PM, Norbert Lange wrote:
>>> I works, because collect2 (the "compiler driver", which documents
>>> the -r option) now knows about the -r flag, using -Wl,-[U]r would
>>> mean the flags aren't even looked at.
>>> It can then disable functionality that is not supposed to be done at
>>> this point (see gcc/collect2.c, search for 'early_exit'). It might
>>> actually be in conflict with the -Ur option from the comments, but I
>>> don't know what this is trying to solve (the constructor tables
>>> would then be built in the second step?)
>>>
>>> I would prefer the compiler driver knowing about the flags and
>>> correctly dealing with them, instead of replicating this logic in
>>> scripts (and keeping it up to date with this internal logic).  
>>
>> Ack.
>>
>>> Might be that your wrapper script is doing something similarly by
>>> filtering out the arguments for the first step, which might be the
>>> same functionally that is skipped when adding '-r'
>>>
>>> I dont know what the -Ur flag is trying to solve, and the first
>>> patch adding -no-pie is way less likely to change something (given
>>> that I would not have compiled with -pie before).
>>> The new patch would however leave more of the magic to the toolchain
>>> and seems more "correct" to me, for whatever that's worth. But it
>>> might have some subtle differences to before, got some testcase
>>> where lacking the -Ur flag made a difference?  
>>
>> I don't know the original intent about passing -Ur to the linker,
>> except maybe to stick to the ld manpage which states that the last
>> partial link command should be given such option.
>>
>> However my understanding is that we don't need it in wrap-link.sh,
>> since the script eventually completes the link stage to produce a
>> fully resolved executable. That implies collecting the ctors/dtors and
>> resolving all references from the partially linked object file anyway.
>>
>> Some testing only passing -r here seems to confirm this assumption
>> with C++ apps; C++ users may want to check this too:
> 
> I just told some C++ power users to give that a try. I am not sure how
> fast the feedback will arrive, i hope in the next two weeks.
> 

Ok, thanks.

-- 
Philippe.



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