Re: Method to get LTTNG-UST version during runtime?

[Norbert Lange via lttng-dev <lttng-dev@lists.lttng.org>]

I dont want to use anything else, I just want  to add instrumentation
for dynamically loaded tracepoints that does next to nothing if not
activated (see [1]).
liblttng-ust-ctl is not even ABI compatible between 2.13 and 2.14
(different soname), so that's pretty useless since it already binds to
either 2.13 or 2.14 at compile-time.

[1] - https://lists.lttng.org/pipermail/lttng-dev/2021-May/030004.html

Norbert

Am Mo., 23. Juni 2025 um 16:21 Uhr schrieb Kienan Stewart
<kstewart@efficios.com>:
>
> Hi Norbert,
>
> If you link to liblttng-ust-ctl, you can use `lttng_ust_ctl_get_version`.
>
> thanks,
> kienan
>
>
> On 6/18/25 11:22 AM, Norbert Lange via lttng-dev wrote:
> > Hi,
> >
> > there are some substantial changes in 2.14.0 that afffect how/if
> > tracing is possible.
> > For ex. c246521ddcba1d1d28cfa0482aa500b9122e7264 allows doing more work upfront
> > by calling lttng_ust_init_thread().
> > With 2.13.x the same code will instead do various syscalls or
> > allocations during the first tracepoints, violating realtime
> > constraints and possible abort the process.
> >
> > I miss an easy method to inspect the Lttng UST Version for checks or
> > workarounds.
> >
> > There is the lttng_ust_loaded variable that could be abused to carry
> > an packed version instead of 1. (Of course that could always cause
> > fallout)
> >
> > Regards, Norbert
>