[Xenomai] Won`t build on new Debian Stable

Norbert Lange nolange79 at gmail.com
Fri Oct 13 09:40:54 CEST 2017


Ok I just realized there is a "-Ur" option, aside from "-U -r".

You get alot otherwise undocumented flags with "gcc --help -v" BTW

2017-10-13 9:13 GMT+02:00 Norbert Lange <nolange79 at gmail.com>:
> Hello,
>
> I tracked down the source of information to this:
> https://wiki.ubuntu.com/SecurityTeam/PIE
>
> I changed the flags from "-Wl,-Ur" to "-Wl,-U -r", so you wont get an
> explanation from me, why -U has to be passed for the linker.
> And by the way, gcc accepts -U aswell, so this might be preferable to
> be used directly too.
>
> I don`t know why those flags aren' t documented, bug in gcc
> documentation? As far as I understand is that gcc is smart enough to
> correctly deal with the flags gcc directly received, but the linker
> lacks that information.
>
> I don' t know what the issue is with the C++ Constructors, in the
> context of this change?
> (I heard about the issues if those reside in a shared library, use
> function from libcobald and don't depend on libcobald. Which is more
> of a broken build to me if you don't add the depended libs, and will
> bite you the same way if you use GCCs constructor attribute)
>
> Kind regards,
> Norbert.
>
> 2017-10-12 10:33 GMT+02:00 Henning Schild <henning.schild at siemens.com>:
>> Hey Norbert,
>>
>> thanks for looking into that again! Could you please explain how and
>> why that works, or point out what to look at in flint? Mailing list
>> thread, commit, something like that.
>>
>> As far as i can see gcc now gets a "-r" which i do not find in the
>> manpage. And ld gets a "-U" which i do not find in its manpage. And
>> there is something about c++ constructors which might change the
>> behaviour of xenomai.
>>
>> Henning
>>
>> Am Tue, 10 Oct 2017 16:38:50 +0200
>> schrieb Norbert Lange <nolange79 at gmail.com>:
>>
>>> Some highly trivial fix attached!
>>> Its strange that this flag is not documented in the manual (I found
>>> out abaout this fix from https://launchpad.net/ubuntu/+source/flint)
>>>
>>> Norbert Lange
>>>
>>> 2017-08-10 11:49 GMT+02:00 Henning Schild
>>> <henning.schild at siemens.com>:
>>> > Hi Norbert,
>>> >
>>> > Thanks! In fact that issue has come up before and a similar
>>> > workaround was described. It should be fixed, patches welcome!
>>> >
>>> > Henning
>>> >
>>> > Am Wed, 9 Aug 2017 16:21:02 +0200
>>> > schrieb Norbert Lange <nolange79 at gmail.com>:
>>> >
>>> >> Hello,
>>> >>
>>> >> Building the xenomai package won`t work because debian now
>>> >> defaults to using pie, and the linker will complain with "ld: -r
>>> >> and -pie may not be used together"
>>> >>
>>> >> A workaround for now is to add the flags manually:
>>> >> ../xenomai-3.0.5/configure LDFLAGS=-no-pie CFLAGS="-fno-PIE
>>> >> -fno-pie -no-pie"
>>> >>
>>> >> A real fix would be similar to
>>> >> http://lists.gnu.org/archive/html/bug-grub/2016-11/msg00011.html
>>> >> (no-pie is not supported on old and other compilers)
>>> >>
>>> >> Kind regards,
>>> >> Norbert
>>> >>
>>> >> _______________________________________________
>>> >> Xenomai mailing list
>>> >> Xenomai at xenomai.org
>>> >> https://xenomai.org/mailman/listinfo/xenomai
>>> >
>>



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