2 id: liblttng‑ust‑dl
5 This LTTng-UST helper causes all calls to `dlopen()` and `dlclose()`
6 in the target application to be traced with LTTng.
8 The helper's shared object, `liblttng-ust-dl.so`, registers the
9 following tracepoints when preloaded:
12 <table class="func-desc">
15 <th><abbr title="Tracepoint">TP</abbr> provider name</th>
16 <th><abbr title="Tracepoint">TP</abbr> name</th>
17 <th>Description/fields</th>
23 <code class="no-bg">ust_baddr</code>
26 <code class="no-bg">push</code>
29 <p><code>dlopen()</code> call</p>
33 <code class="arg">baddr</code> memory
35 (where the dynamic linker placed the shared
39 <code class="arg">sopath</code> file system
40 path to the loaded shared object
43 <code class="arg">size</code> file size
44 of the the loaded shared object
47 <code class="arg">mtime</code> last
48 modification time (seconds since Epoch time)
49 of the loaded shared object
56 <code class="no-bg">pop</code>
59 <p><code>dlclose()</code> call</p>
63 <code class="arg">baddr</code> memory
73 To use this LTTng-UST helper with any user application, independently of
74 how the latter is built, do:
77 LD_PRELOAD=liblttng-ust-dl.so my-app
80 Of course, like any other tracepoint, the ones above need to be enabled
81 in order for LTTng-UST to generate events. This is done using the
82 `lttng` command line tool
83 (see [Controlling tracing](#doc-controlling-tracing)).