Document LGPL TRACEPOINT_CREATE_PROBES restrictions

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/include/lttng/tracepoint-event.h b/include/lttng/tracepoint-event.h
index e7ea461bcdb87dfd6cdb17673cf9712f8cb8b3fa..b47bf6a7b4efe3007125bd9ce3f7bc537b073c37 100644 (file)
--- a/include/lttng/tracepoint-event.h
+++ b/include/lttng/tracepoint-event.h
@@ -35,6 +35,19 @@
  *       #define TRACEPOINT_INCLUDE_PATH .
  *     combined with -Ipath_to_header as compiler argument to allow
  *     searching for a header within your project build tree.
+ *
+ * Note considering licensing:
+ *
+ * Including the tracepoint-event.h header without the
+ * TRACEPOINT_CREATE_PROBES macro defined is fine within any application
+ * source code, even for non-LGPL-compatible applications.
+ *
+ * However, TRACEPOINT_CREATE_PROBES should only be defined within
+ * LGPL-compatible C files. This means that the tracepoint probe object
+ * should be relinkable when distributed, either by providing it as a
+ * dynamically linkable shared object (.so library), or by providing the
+ * build scripts and object files required to relink the object if
+ * statically linked.
  */
 
 #ifdef __cplusplus

diff --git a/tests/demo/tp.c b/tests/demo/tp.c
index d3c7d5367d2652f1469fba3a22add88a76d06b3d..9f77499046646eaea56d73df89415f835965b7d4 100644 (file)
--- a/tests/demo/tp.c
+++ b/tests/demo/tp.c
@@ -18,5 +18,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/*
+ * Note: TRACEPOINT_CREATE_PROBES can only be defined within LGPL C
+ * files. See comment in lttng/tracepoint-event.h for detail.
+ */
 #define TRACEPOINT_CREATE_PROBES
 #include "ust_tests_demo.h"

diff --git a/tests/hello/tp.c b/tests/hello/tp.c
index 509f5a4912d625b687846403f185404a4ac1255e..01adef16c20b0917132715225c5c9f747dc9fd99 100644 (file)
--- a/tests/hello/tp.c
+++ b/tests/hello/tp.c
@@ -18,5 +18,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/*
+ * Note: TRACEPOINT_CREATE_PROBES can only be defined within LGPL C
+ * files. See comment in lttng/tracepoint-event.h for detail.
+ */
 #define TRACEPOINT_CREATE_PROBES
 #include "ust_tests_hello.h"