[Buildroot] [PATCH 1/1] Fix build of lttng-libust

[Norbert Lange]

2017-11-05 17:13 GMT+01:00 Arnout Vandecappelle <arnout at mind.be>:
>
>
> On 31-10-17 11:20, Norbert Lange wrote:
>> Hello Thomas,
>>
>> I dont know about the autobuilder (can I upload configs to test
>> there?), this is an issue I encountered with a private buildroot
>> config.
>> I tried to reduce it as much as possible, and added the defconfig.
>>
>> 2017-10-30 20:40 GMT+01:00 Thomas Petazzoni
>> <thomas.petazzoni at free-electrons.com>:
>>> Hello,
>>>
>>> On Mon, 30 Oct 2017 17:31:21 +0100, Norbert Lange wrote:
>>>> The build of doc/examples/cmake-multiple-shared-libraries
>>>> does fail as a dependend library is missing.
>>>> This issue is not specific to builroot and should ideally
>>>> be fixed upstream (Issue: https://bugs.lttng.org/issues/1132)
>>>>
>>>> The fix is done without any indepth knowledge of the CMake
>>>> mechanisms, but seems to work correctly
>>>>
>>>> Signed-off-by: Norbert Lange <norbert.lange at andritz.com>
>>>
>>> Which specific build problem are you fixing? Is this a problem that has
>>> been found by http://autobuild.buildroot.org? If that's the case, we
>>> like to include a reference to such an autobuilder failure in the
>>> commit log.
>
>  It has not been found by the autobuilders, the only failure is
> http://autobuild.buildroot.net/results/c86a82b2fd41316a7a451b20d9274d5c95f89baa
> and that's due to CMake version.

So, is that a problem, or even something I should do anything about?
I am not sure why you bring this up repeatedly.

>
>  The build error is:
>
> output/host/lib/gcc/x86_64-buildroot-linux-gnu/7.2.0/../../../../x86_64-buildroot-linux-gnu/bin/ld:
> warning: liblttng-ust-tracepoint.so.0, needed by
> output/build/lttng-libust-2.9.0/liblttng-ust/.libs/liblttng-ust.so, not found
> (try using -rpath or -rpath-link)
> output/build/lttng-libust-2.9.0/liblttng-ust/.libs/liblttng-ust.so: undefined
> reference to `exit_tracepoint'
> output/build/lttng-libust-2.9.0/liblttng-ust/.libs/liblttng-ust.so: undefined
> reference to `__tracepoint_probe_unregister_queue_release'
> output/build/lttng-libust-2.9.0/liblttng-ust/.libs/liblttng-ust.so: undefined
> reference to `__tracepoint_probe_register_queue_release'
> output/build/lttng-libust-2.9.0/liblttng-ust/.libs/liblttng-ust.so: undefined
> reference to `__tracepoint_probe_prune_release_queue'
> output/build/lttng-libust-2.9.0/liblttng-ust/.libs/liblttng-ust.so: undefined
> reference to `init_tracepoint'
> collect2: error: ld returned 1 exit status

So I take, you can reproduce it.

>
>  The weird thing is: liblttng-ust.so.0 does have the correct RPATH to find the
> tracepoint library. And on all other builds I tried (and apparently including
> all the autobuilders), it does find it. So I guess it's either binutils 2.29 or
> GCC 7's LTO plugin that is acting up somehow...

LTO doesn't seem involved (I think?)

>
>
>  Since this is anyway just an example, wouldn't it be better to just disable the
> documentation entirely? I.e. teach configure.ac to understand --disable-doc and
> teach Makefile.am to not recurse into doc if docs are disabled?

No problem with that, for the upstream package this might be more of an issue.
I am certainly curious where this issue comes from, and what other problems
could be showing up. Whether this is a lttng, CMake, gcc or binutils issue...

>
>  Regards,
>  Arnout
>
> --
> Arnout Vandecappelle                          arnout at mind be
> Senior Embedded Software Architect            +32-16-286500
> Essensium/Mind                                http://www.mind.be
> G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
> LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
> GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF