From: Francis Deslauriers <francis.deslauriers@efficios.com>
Date: Mon, 20 Apr 2020 21:33:48 +0000 (-0400)
Subject: doc: Explain `struct lttng_bytecode_runtime` layout restrictions
X-Git-Tag: v2.13.0-rc1~498
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=73d37531c6b12d24086681e636fae8cf0375d2dd;p=lttng-ust.git

doc: Explain `struct lttng_bytecode_runtime` layout restrictions

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I875b11c644917a3b9f15bf88ab44098813e59db0
---

diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index 54eb0955..b050d30e 100644
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -459,6 +459,12 @@ enum lttng_filter_ret {
 	/* Other bits are kept for future use. */
 };
 
+/*
+ * This structure is used in the probes. More specifically, the `filter` and
+ * `node` fields are explicity used in the probes. When modifying this
+ * structure we must not change the layout of these two fields as it is
+ * considered ABI.
+ */
 struct lttng_bytecode_runtime {
 	/* Associated bytecode */
 	struct lttng_ust_filter_bytecode_node *bc;