[lttng-dev] [PATCH lttng-ust] Improve tracelog handling, reduce exported functions

[Norbert Lange]

Am Do., 20. Mai 2021 um 19:18 Uhr schrieb Mathieu Desnoyers
<mathieu.desnoyers at efficios.com>:
>
>
>
> ----- On May 20, 2021, at 12:51 PM, Norbert Lange nolange79 at gmail.com wrote:
>
> > Am Do., 20. Mai 2021 um 18:25 Uhr schrieb Mathieu Desnoyers
> > <mathieu.desnoyers at efficios.com>:
> >>
> >> ----- On May 20, 2021, at 11:54 AM, Norbert Lange nolange79 at gmail.com wrote:
> >> [...]
> >>
> >> >> What prevents you from linking against lttng-ust.so again ?
> >> >
> >> > I did not poke around enough with Lttng to be confident it wont have
> >> > side effects,
> >> > I really don't want it active in production. It doesn't seem there is
> >> > much public knowledge with Xenomai either.
> >> > lttng-ust.so will spawn threads, lttng-ust-tracepoint.so is mostly passive,
> >>
> >> There is indeed a split between instrumentation and runtime threads done
> >> with lttng-ust-tracepoint.so vs lttng-ust.so.
> >>
> >> I understand that this split is missing for tracelog and tracef, and
> >> would be a good thing to have.
> >>
> >> I would be interested to move the tracelog and tracef implementation
> >> from liblttng-ust.so to liblttng-ust-tracepoint.so, even this late
> >> in the -rc cycle, because all users of tracelog/tracef need to link
> >> against liblttng-ust-tracepoint.so anyway. So moving these symbols
> >> should not affect anyone.
> >>
> >> Can you give it a try and let me know if it works for you ?
> >
> > Will take some time, whats the timeframe you need for feedback?
>
> Here is the tentative commit:
>
> https://review.lttng.org/c/lttng-ust/+/5927 Move tracef/tracelog symbols to liblttng-ust-tracepoint.so
>

Make a own thread for this?
I testet this, but get errors as liblttng-ust-tracepoint.so depends on
symbols from liblttng-ust.so.

/usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/bin/ld:
/tmp/opt/hipase2/buildroot-acpu/host/x86_64-buildroot-linux-gnu/sysroot/lib/../lib64/liblttng-ust-tracepoint.so:
undefined reference to `lttng_ust_probe_register'
/usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/bin/ld:
/tmp/opt/hipase2/buildroot-acpu/host/x86_64-buildroot-linux-gnu/sysroot/lib/../lib64/liblttng-ust-tracepoint.so:
undefined reference to `lttng_ust_probe_unregister'