From 9f13d176b39efcaa60e586abf7a6dc8f0545e7d1 Mon Sep 17 00:00:00 2001
From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Fri, 4 Sep 2015 17:09:39 -0400
Subject: [PATCH] Document kernel events filtering

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
---
 contents/understanding-lttng/core-concepts/domain.md |  7 +++----
 .../controlling-tracing/enabling-disabling-events.md | 12 +++++++-----
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/contents/understanding-lttng/core-concepts/domain.md b/contents/understanding-lttng/core-concepts/domain.md
index b0cb528..e0631ea 100644
--- a/contents/understanding-lttng/core-concepts/domain.md
+++ b/contents/understanding-lttng/core-concepts/domain.md
@@ -20,7 +20,6 @@ source code), you need to specify which one is concerned when enabling
 an event because both domains could have existing events with the same
 name.
 
-Some features are not available in all domains. Filtering enabled
-events using custom expressions, for example, is currently not
-supported in the kernel domain, but support could be added in the
-future.
+Some features are reserved for some domains. Dynamic function entry/return
+instrumentation, for example, is currently only supported in the kernel
+domain, but support for other domains could be added in the future.
diff --git a/contents/using-lttng/controlling-tracing/enabling-disabling-events.md b/contents/using-lttng/controlling-tracing/enabling-disabling-events.md
index 26ab44e..5c40f4c 100644
--- a/contents/using-lttng/controlling-tracing/enabling-disabling-events.md
+++ b/contents/using-lttng/controlling-tracing/enabling-disabling-events.md
@@ -16,13 +16,13 @@ composed of:
      (required).
   2. One or many **instrumentation points** in source code or binary
      program (tracepoint name, address, symbol name, function name,
-     logger name, amongst other types of probes) to be executed (required).
+     logger name, amongst other types of probes) to be executed
+     (required).
   3. A **log level** (each instrumentation point declares its own log
      level) or log level range to match (optional; only valid for user
      space domain).
   4. A **custom user expression**, or **filter**, that must evaluate to
-     _true_ when a tracepoint is executed (optional; only valid for user
-     space domain).
+     _true_ when a tracepoint is executed (optional).
 
 All conditions are specified using arguments passed to the
 `enable-event` command of the `lttng` tool.
@@ -80,6 +80,8 @@ lttng enable-event -k --tracepoint sched_switch
 lttng enable-event -k --tracepoint gpio_value
 lttng enable-event -k --function usb_probe_device usb_probe_device
 lttng enable-event -k --syscall --all
+lttng enable-event -k --tracepoint irq_handler_entry  \
+                   --filter 'irq == 28 || irq == 17'
 </pre>
 
 The wildcard symbol, `*`, matches _anything_ and may only be used at
@@ -89,8 +91,8 @@ undesired shell expansion.
 
 System call events can be enabled individually, too:
 
-<pre class="term">
-lttng enable-event -k --syscall open
+<pre class="term" style="position: relative">
+<div class="since">Since 2.6</div>lttng enable-event -k --syscall open
 lttng enable-event -k --syscall read
 lttng enable-event -k --syscall fork,chdir,pipe
 </pre>
-- 
2.34.1