[lttng-dev] [Patch LTTng-ust 7/7] Update the LTTng documentation with CTF named enumerations

[Geneviève Bastien]

Signed-off-by: Geneviève Bastien <gbastien+lttng at versatic.net>
---
 doc/man/lttng-ust.3 | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/doc/man/lttng-ust.3 b/doc/man/lttng-ust.3
index 7624e88..d474225 100644
--- a/doc/man/lttng-ust.3
+++ b/doc/man/lttng-ust.3
@@ -158,6 +158,14 @@ TRACEPOINT_EVENT(
 		 */
 		ctf_float(float, floatfield, floatarg)
 		ctf_float(double, doublefield, doublearg)
+
+		/*
+		 * ctf_enum: a field using a previously defined named enumeration
+		 * args: (provider, enum name, field name, argument expression)
+		 * The enumeration itself and its values must have been defined
+		 * previously with the TRACEPOINT_ENUM macro, described below.
+		 */
+		ctf_enum(sample_component, enumeration_name, enumfield, enumarg)
 	)
 )
 
@@ -165,6 +173,52 @@ There can be an arbitrary number of tracepoint providers within an
 application, but they must each have their own provider name. Duplicate
 provider names are not allowed.
 
+The CTF specification also supports some named basic and compound types that
+can be defined inside a tracepoint provider and used as fields in the
+tracepoint. This shows how to specify them and what they can be used for:
+
+The enumeration is a mapping between an integer and a string. It can be used
+to have a more compact trace in cases where the possible values for a field are
+limited:
+
+TRACEPOINT_ENUM(
+	/*
+	 * The provider name, as described in the TRACEPOINT_EVENT macro
+	 */
+	sample_component,
+
+	/*
+	 * The name of this enumeration, that will be used when using this
+	 * metadata type in tracepoint fields
+	 */
+	enumeration_name,
+
+	/*
+	 * Integer type by which this enumeration will be represented.
+	 * It can be: char, int, long or any variant on those
+	 */
+	type,
+
+	/*
+	 * TP_ENUM_VALUES describe the values of this enumeration and what they
+	 * map to.
+	 */
+	TP_ENUM_VALUES(
+		/*
+		 * Maps an integer with this string value. By default, enumerations
+		 * start at 0 and increment 1 for each entry.
+		 */
+		ctf_enum_value(string_value)
+
+		/*
+		 * Maps the string value to integers in the range 'start' to 'end'
+		 * inclusively. If 'start' == 'end', then the string is mapped to
+		 * a specific value.
+		 */
+		ctf_enum_range(start, end, string_value)
+	)
+)
+
 .fi
 
 .SH "ASSIGNING LOGLEVEL TO EVENTS"
-- 
1.8.5.3