contents/understanding-lttng/plumbing/lttng-modules.md

   1 ---
   2 id: lttng-modules
   3 ---
   4
   5 The LTTng Linux kernel modules provide everything needed to trace the
   6 Linux kernel: various probes, a ring buffer implementation for a
   7 consumer daemon to read trace data and the tracer itself.
   8
   9 Only in exceptional circumstances should you ever need to load the
  10 LTTng kernel modules manually: it is normally the responsability of
  11 `root`'s session daemon to do so. Even if you were to develop your
  12 own LTTng probe module&mdash;for tracing a custom kernel or some kernel
  13 module (this topic is covered in the
  14 [Linux kernel](#doc-instrumenting-linux-kernel) instrumenting guide of
  15 the [Using LTTng](#doc-using-lttng) chapter)&mdash;you
  16 should use the `--extra-kmod-probes` option of the session daemon to
  17 append your probe to the default list. The session and consumer daemons
  18 of regular users do not interact with the LTTng kernel modules at all.
  19
  20 LTTng kernel modules are installed, by default, in
  21 <code>/usr/lib/modules/<em>release</em>/extra</code>, where
  22 <code><em>release</em></code> is the kernel release
  23 (see `uname --kernel-release`).