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Hi Jonathan,</div>
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You are absolutely right !</div>
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I have two different lttng : <span style="color:rgb(32, 31, 30);font-family:"Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif;font-size:14.6667px;background-color:rgb(255, 255, 255);display:inline !important">
find /usr -name "*liblttng-ust*" </span><a href="https://paste.ubuntu.com/p/NVtXPhj4fW/" style="font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 14.6667px;">Ubuntu
Pastebin</a></div>
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<br>
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According to you, what would be the best solution to solve this issue ?</div>
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I have indeed a folder named lttng-ust where I have made the (wrong) configure / make.</div>
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I tried to (temporary) remove all the libttng* /usr/local/lib/, but I face this problem : </div>
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/usr/bin/ld: hello-tp.o: in function `__lttng_events_init__hello_world':
<div>hello-tp.c:(.text+0xe56): undefined reference to `lttng_ust_probe_register'</div>
<div>/usr/bin/ld: hello-tp.o: in function `__lttng_events_exit__hello_world':</div>
<div>hello-tp.c:(.text+0xeb2): undefined reference to `lttng_ust_probe_unregister'</div>
<div>collect2: error: ld returned 1 exit status</div>
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In the worst case scenario I am able to get my last clean snapchot.</div>
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What would you advise me to do ?</div>
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Cheers,</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>De :</b> Jonathan Rajotte-Julien <jonathan.rajotte-julien@efficios.com><br>
<b>Envoyé :</b> mercredi 24 mars 2021 17:36<br>
<b>À :</b> MONTET Julien <julien.montet@reseau.eseo.fr><br>
<b>Cc :</b> lttng-dev <lttng-dev@lists.lttng.org><br>
<b>Objet :</b> Re: [lttng-dev] Issues on basic LTTng trace userspace (tutorial)</font>
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<div class="PlainText">Hi Julien,<br>
<br>
> TBH nothing points toward a problem here. I would need to spawn a 20.04 to check<br>
> if something is broken, I might have time later today.<br>
<br>
Finally I had a Vagrant definition file laying around for the stable-2.12 ppa<br>
that let me bring up a vm easily. All seems fine.<br>
<br>
How lttng is installed:<br>
<br>
add-apt-repository ppa:lttng/stable-2.12 -y<br>
apt-get update<br>
apt-get install -y lttng-tools lttng-modules-dkms babeltrace2 liblttng-ust-dev<br>
<br>
>From there all the steps for building the userspace application works without<br>
ANY modifications.<br>
<br>
The app is able to connect itself to the global sessiond: <a href="https://paste.ubuntu.com/p/QnfqbtgpFF/">
https://paste.ubuntu.com/p/QnfqbtgpFF/</a><br>
<br>
Note that no local sessiond is present hence why the app does not communicate<br>
with one.<br>
<br>
Note that the user I am using here (vagrant) is not part of the "tracing" group<br>
hence the user cannot interact with the global sessiond.<br>
<br>
Such scenario return the following:<br>
<br>
vagrant@ubuntu2004:~$ lttng list -u<br>
Error: Unable to list UST events: No session daemon is available<br>
<br>
Now let's start a lttng-sessiond for the user and restart our app (note that<br>
this is not required for day to day tracing since a running app will connect<br>
itself and only for debugging purpose):<br>
<br>
lttng-sessiond -b<br>
LTTNG_UST_DEBUG=1 ./hello<br>
<br>
Yielding: <a href="https://paste.ubuntu.com/p/MsnHt94FXZ/">https://paste.ubuntu.com/p/MsnHt94FXZ/</a><br>
<br>
Now the app is connected to both sessiond.<br>
<br>
Now the user can list the event against the local lttng-sessiond:<br>
<br>
vagrant@ubuntu2004:~$ lttng list -u<br>
UST events:<br>
-------------<br>
<br>
PID: 15429 - Name: ./hello<br>
lttng_ust_tracelog:TRACE_DEBUG (loglevel: TRACE_DEBUG (14)) (type: tracepoint)<br>
lttng_ust_tracelog:TRACE_DEBUG_LINE (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)<br>
<br>
<br>
So based on this I would say that either we are not given the full picture of<br>
what is going on or there is a step you are missing. One explication would be<br>
that you end up linking against a older lttng-ust without knowing it.<br>
<br>
Please run this an provide the output via a paste service:<br>
<br>
find /usr -name "*liblttng-ust*"<br>
<br>
For example on my VM: <a href="https://paste.ubuntu.com/p/Tjxn3V7g5j/">https://paste.ubuntu.com/p/Tjxn3V7g5j/</a><br>
<br>
Cheers<br>
<br>
-- <br>
Jonathan Rajotte-Julien<br>
EfficiOS<br>
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