IB/umad: Clarify documentation of transaction ID
Signed-off-by: Hal Rosenstock <halr@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/Documentation/infiniband/user_mad.txt b/Documentation/infiniband/user_mad.txt
index 750fe5e..8ec54b9 100644
--- a/Documentation/infiniband/user_mad.txt
+++ b/Documentation/infiniband/user_mad.txt
@@ -91,6 +91,14 @@
if (ret != sizeof *mad + mad_length)
perror("write");
+Transaction IDs
+
+ Users of the umad devices can use the lower 32 bits of the
+ transaction ID field (that is, the least significant half of the
+ field in network byte order) in MADs being sent to match
+ request/response pairs. The upper 32 bits are reserved for use by
+ the kernel and will be overwritten before a MAD is sent.
+
Setting IsSM Capability Bit
To set the IsSM capability bit for a port, simply open the