docs: Add supported versions and fix-backport policy

[lttng-tools.git] / README.adoc

// Render with Asciidoctor

:nbh: ‑
:lt: LTTng{nbh}tools
:lib: liblttng{nbh}ctl

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= {lt}
5 May 2020

[.normal]
https://ci.lttng.org/job/lttng-tools_master_linuxbuild/[image:https://img.shields.io/jenkins/build.svg?jobUrl=https://ci.lttng.org/job/lttng-tools_master_linuxbuild/[Jenkins, title="Jenkins"]]
https://scan.coverity.com/projects/lttng-tools[image:https://img.shields.io/coverity/scan/lttng-tools.svg[Coverity, title="Coverity"]]

[.lead]
_**{lt}**_ is a set of components to control https://lttng.org/[LTTng]
tracing.

The project includes:

* The LTTng https://lttng.org/man/8/lttng-sessiond/[session daemon].

* The LTTng consumer daemon.

* The LTTng https://lttng.org/man/8/lttng-relayd/[relay daemon].

* {lib}, a library with a C{nbsp}API used to communicate with
  the session daemon.

* Python{nbsp}3 bindings of liblttng{nbh}ctl.

* https://lttng.org/man/1/lttng/[`lttng`], a command-line tool over
  {lib}.

* https://lttng.org/man/1/lttng-crash/[`lttng{nbh}crash`], a command-line
  tool to recover and view LTTng{nbsp}2 trace buffers in the event of a
  crash.

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== Required and optional dependencies

You need the following dependencies to build and run the {lt}
components:

* **Linux kernel{nbsp}≥{nbsp}2.6.30**

* **http://www.liburcu.org/[Userspace{nbsp}RCU]{nbsp}≥{nbsp}0.14.0**.
+
Debian/Ubuntu package: `liburcu{nbh}dev`.

* **popt{nbsp}≥{nbsp}1.13**
+
Debian/Ubuntu package: `libpopt{nbh}dev`.

* **http://xmlsoft.org/[Libxml2]{nbsp}≥{nbsp}2.7.6**
+
Debian/Ubuntu package: `libxml2{nbh}dev`

The following dependencies are optional:

* **https://babeltrace.org/[Babeltrace{nbsp}2]**: default viewer
  of the https://lttng.org/man/1/lttng-view/[`lttng view`] command,
  `make{nbsp}check` and tests.
+
Debian/Ubuntu package: `babeltrace2 libbabeltrace2-dev`

* **https://lttng.org/[LTTng{nbh}UST]** (same minor version as {lt}):
  LTTng user space tracing (applications and libraries).
+
Debian/Ubuntu package: `liblttng{nbh}ust{nbh}dev`

* **https://www.python.org/[Python]{nbsp}≥{nbsp}3.4**:
  `make{nbsp}check` and tests.
+
Debian/Ubuntu package: `python3`

* **http://www.swig.org/[SWIG]{nbsp}≥{nbsp}2.0** and
  **Python{nbsp}3 development headers**: Python bindings
  (enabled at <<configure,build configuration>> time with the
  `{nbh}{nbh}enable{nbh}python{nbh}bindings` option).
+
Debian/Ubuntu packages: `swig2.0` and `python3{nbh}dev`

* **modprobe** and/or
  **https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/[kmod]{nbsp}≥{nbsp}22**:
  automatic LTTng kernel modules loading (kernel tracing).

* **Bash**: `make{nbsp}check`.

* **http://man7.org/linux/man-pages/man1/man.1.html[`man`]**
  (manual pager): view `lttng` command manual
  pages with the `{nbh}{nbh}help` option or with the
  https://lttng.org/man/1/lttng-help/[`lttng{nbsp}help`] command.
+
NOTE: You can use the <<configure,build configuration>> option
`{nbh}{nbh}enable{nbh}embedded{nbh}help` to embed the manual pages into
the `lttng`, `lttng{nbh}sessiond`, `lttng{nbh}relayd`, and
`lttng{nbh}crash` programs so that you don't need `man` to view them.

* **http://perfmon2.sourceforge.net/[libpfm]{nbsp}≥{nbsp}4.0**:
  perf regression test suite.
+
Debian/Ubuntu package: `libpfm4-dev`

{lt} supports both the LTTng Linux kernel tracer and LTTng user space
tracer sharing the same _minor_ version. While some minor releases do
not change the tracer ABIs and _could_ work, no testing is performed to
ensure that cross-version compatibility is maintained.

You don't need to rebuild or modify applications instrumented with older
versions of the LTTng{nbh}UST project to make them work with the
components of the latest {lt} release.

See the https://lttng.org/docs/[LTTng Documentation] for more
information on versioning.

== Build from source

=== Dependencies

You need the following tools to build {lt}:

* **https://www.gnu.org/software/automake/manual/html_node/Autotools-Introduction.html[GNU{nbsp}Autotools]**
  (**Automake{nbsp}≥{nbsp}1.12**,
  **Autoconf{nbsp}≥{nbsp}2.64**, and **Autoheader{nbsp}≥{nbsp}2.50**)

* **http://www.gnu.org/software/autoconf/[GNU{nbsp}Libtool]{nbsp}≥{nbsp}2.2**

* **https://github.com/westes/flex/[Flex]{nbsp}≥{nbsp}2.5.35**

* **https://www.gnu.org/software/bison/[Bison]{nbsp}≥{nbsp}2.4**

To build the {lt} manual pages:

* **https://asciidoc.org/[AsciiDoc]{nbsp}≥{nbsp}8.4.5**
+
NOTE: Previous versions could work, but were not tested.

* **https://pagure.io/xmlto[xmlto]{nbsp}≥{nbsp}0.0.21**
+
NOTE: Previous versions could work, but were not tested.

If you use GNU{nbsp}gold, which is _not_ mandatory:

* **GNU{nbsp}gold{nbsp}≥{nbsp}2.22**

NOTE: With GNU{nbsp}gold, you might need to add
`-L/usr/local/lib` to the `LDFLAGS` environment variable.

=== Build steps

. **If you have the {lt} Git source**, run:
+
----
$ ./bootstrap
----
+
This script creates the `configure` script.

. [[configure]]Configure the build:
+
--
----
$ ./configure
----

If you want the {lib} Python bindings, use the
`{nbh}{nbh}enable{nbh}python{nbh}bindings` option. See also the `PYTHON`
and `PYTHON_CONFIG` environment variables in
`./configure{nbsp}{nbh}{nbh}help`.

If you don't want to build the manual pages, use the
`{nbh}{nbh}disable{nbh}man{nbh}pages` option.

If you want to embed the manual pages into the `lttng`,
`lttng{nbh}sessiond`, `lttng{nbh}relayd`, and `lttng{nbh}crash` programs
so that you don't need `man` to view them, use the
`{nbh}{nbh}enable{nbh}embedded{nbh}help` option.

This build configuration script finds LTTng{nbh}UST with
https://www.freedesktop.org/wiki/Software/pkg-config/[pkg{nbh}config]:
set the `PKG_CONFIG_PATH` environment variable accordingly if
pkg{nbh}config cannot find the `lttng{nbh}ust` package information.

See `./configure{nbsp}{nbh}{nbh}help` for the complete list of options.
--

. Build the project:
+
----
$ make
----

. Install the project:
+
----
$ sudo make install
$ sudo ldconfig
----

== Usage

See the https://lttng.org/docs/#doc-controlling-tracing[Tracing control]
section of the LTTng Documentation to learn how to use the {lt}
components.

See also the https://lttng.org/man/[LTTng manual pages] (all
section{nbsp}1 and{nbsp}8 pages).

As there's no official {lib} Python bindings yet, see
link:doc/python-howto.txt[`doc/python-howto.txt`] to understand how to
use them.

== Supported versions

The LTTng project supports the last two released stable versions
(e.g. stable-2.13 and stable-2.12).

Fixes are backported from the master branch to the last stable version unless
those fixes would break the ABI or API. Those fixes may be backported to the
second-last stable version, depending on complexity and ABI/API compatibility.

Security fixes are backported from the master branch to both of the last stable
version and the second-last stable version.

New features are integrated into the master branch and not backported to the
last stable branch.

== Community

Mailing list::
    https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev[lttng-dev]
    (mailto:lttng-dev@lists.lttng.org[lttng-dev@lists.lttng.org])

IRC channel::
    irc://irc.oftc.net/lttng[`#lttng`] on the OFTC network

Bug tracker::
    https://bugs.lttng.org/projects/lttng-tools[{lt} bug tracker]

GitHub project::
    https://github.com/lttng/lttng-tools/[lttng/lttng{nbh}tools]

Continuous integration::
    https://ci.lttng.org/job/lttng-tools_master_build/[{lt}'s master build]
    on LTTng's CI

Code review::
    https://review.lttng.org/q/project:lttng-tools[_lttng{nbh}tools_ project]
    on LTTng Review

Contributor's guide::
    https://github.com/lttng/lttng-tools/blob/master/CONTRIBUTING.md