that, the kernel version may probably be older, but we can't provide
any guarantee. Please let us know if you are able to go lower
without any problems.
- - **[`liburcu`](http://urcu.so/) >= 0.8.0**: userspace RCU library,
+ - **[`liburcu`](http://www.liburcu.org/) >= 0.8.0**: userspace RCU library,
by Mathieu Desnoyers and Paul E. McKenney.
- **`libpopt` >= 1.13**: command line arguments parsing library.
- Debian/Ubuntu package: `libpopt-dev`
- **`libuuid`**: universally unique ID library
- Debian/Ubuntu package: `uuid-dev`
+ - **`libxml2` >= 2.7.6**: XML document parsing library. Needed for
+ tracing session configuration saving/loading and machine interface
+ output support.
+ - Debian/Ubuntu package: `libxml2-dev`
+
The following items are _optional_ dependencies:
- **[Babeltrace](https://lttng.org/babeltrace)**: trace viewer.
Enables the use of `lttng view` command.
- Debian/Ubuntu package: `babeltrace`
- - **`libxml2` >= 2.7.6**: XML document parsing library. Needed for
- tracing session configuration saving/loading and machine interface
- output support.
- - Debian/Ubuntu package: `libxml2-dev`
+ - **[LTTng UST](https://lttng.org) (same minor version as LTTng Tools)**:
+ userspace tracer. Enables the tracing of userspace applications.
+ - Debian/Ubuntu package: `liblttng-ust-dev`
- **Perl**: needed for `make check` and tests.
- **Python >= 3.0**: needed for `make check` and tests.
- Debian/Ubuntu package: `python3`
(kernel tracing).
- **bash**: needed for running `make check`.
+LTTng-tools supports both the [LTTng Linux Kernel tracer](https://lttng.org)
+and [LTTng user space tracer](https://lttng.org) released as part of the same
+**minor** release series. While some releases do not change the tracer ABIs and
+should work with, no testing is performed to ensure cross-version compatibility
+is maintained.
+
+Note that applications instrumented with older versions of the LTTng UST project
+do not have to be rebuilt or modified to work with the latest LTTng-tools.
+For more information on versioning, please refer to the
+[LTTng documentation](https://lttng.org/docs).
Building
--------
portability. Here are some things you should have on your system in
order to compile the Git repository tree:
- - GNU Autotools (Automake >= 1.10, Autoconf >= 2.50,
+ - GNU Autotools (Automake >= 1.10, Autoconf >= 2.64,
Autoheader >= 2.50; make sure your system-wide `automake` points to
a recent version!)
- [GNU Libtool](http://www.gnu.org/software/autoconf/) >= 2.2