-/* Upper bound on the length of a nlattr-formatted flow key. The longest
- * nlattr-formatted flow key would be:
+/* The maximum number of bytes that odp_flow_key_from_flow() appends to a
+ * buffer. This is the upper bound on the length of a nlattr-formatted flow
+ * key that ovs-vswitchd fully understands.
+ *
+ * OVS doesn't insist that ovs-vswitchd and the datapath have exactly the same
+ * idea of a flow, so therefore this value isn't necessarily an upper bound on
+ * the length of a flow key that the datapath can pass to ovs-vswitchd.
+ *
+ * The longest nlattr-formatted flow key appended by odp_flow_key_from_flow()
+ * would be: