net-timestamp: allow reading recv cmsg on errqueue with origin tstamp

[cascardo/linux.git] / Documentation / networking / timestamping.txt

diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt
index 412f45c..b08e272 100644 (file)
--- a/Documentation/networking/timestamping.txt
+++ b/Documentation/networking/timestamping.txt
@@ -122,7 +122,7 @@ SOF_TIMESTAMPING_RAW_HARDWARE:
 
 1.3.3 Timestamp Options
 
-The interface supports one option
+The interface supports the options
 
 SOF_TIMESTAMPING_OPT_ID:
 
@@ -136,7 +136,7 @@ SOF_TIMESTAMPING_OPT_ID:
 
   This option is implemented only for transmit timestamps. There, the
   timestamp is always looped along with a struct sock_extended_err.
-  The option modifies field ee_info to pass an id that is unique
+  The option modifies field ee_data to pass an id that is unique
   among all possibly concurrently outstanding timestamp requests for
   that socket. In practice, it is a monotonically increasing u32
   (that wraps).
@@ -145,6 +145,16 @@ SOF_TIMESTAMPING_OPT_ID:
   stream sockets, it increments with every byte.
 
 
+SOF_TIMESTAMPING_OPT_CMSG:
+
+  Support recv() cmsg for all timestamped packets. Control messages
+  are already supported unconditionally on all packets with receive
+  timestamps and on IPv6 packets with transmit timestamp. This option
+  extends them to IPv4 packets with transmit timestamp. One use case
+  is to correlate packets with their egress device, by enabling socket
+  option IP_PKTINFO simultaneously.
+
+
 1.4 Bytestream Timestamps
 
 The SO_TIMESTAMPING interface supports timestamping of bytes in a