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-rw-r--r--Documentation/networking/packet_mmap.txt30
1 files changed, 28 insertions, 2 deletions
diff --git a/Documentation/networking/packet_mmap.txt b/Documentation/networking/packet_mmap.txt
index 98f71a5cef00..073894d1c093 100644
--- a/Documentation/networking/packet_mmap.txt
+++ b/Documentation/networking/packet_mmap.txt
@@ -8,7 +8,7 @@ capture network traffic with utilities like tcpdump or any other that needs
raw access to network interface.
You can find the latest version of this document at:
- http://pusa.uv.es/~ulisses/packet_mmap/
+ http://wiki.ipxwarzone.com/index.php5?title=Linux_packet_mmap
Howto can be found at:
http://wiki.gnu-log.net (packet_mmap)
@@ -56,7 +56,7 @@ support for PACKET_MMAP, and also probably the libpcap included in your distribu
I'm aware of two implementations of PACKET_MMAP in libpcap:
- http://pusa.uv.es/~ulisses/packet_mmap/ (by Simon Patarin, based on libpcap 0.6.2)
+ http://wiki.ipxwarzone.com/ (by Simon Patarin, based on libpcap 0.6.2)
http://public.lanl.gov/cpw/ (by Phil Wood, based on lastest libpcap)
The rest of this document is intended for people who want to understand
@@ -493,6 +493,32 @@ The user can also use poll() to check if a buffer is available:
pfd.events = POLLOUT;
retval = poll(&pfd, 1, timeout);
+-------------------------------------------------------------------------------
++ PACKET_TIMESTAMP
+-------------------------------------------------------------------------------
+
+The PACKET_TIMESTAMP setting determines the source of the timestamp in
+the packet meta information. If your NIC is capable of timestamping
+packets in hardware, you can request those hardware timestamps to used.
+Note: you may need to enable the generation of hardware timestamps with
+SIOCSHWTSTAMP.
+
+PACKET_TIMESTAMP accepts the same integer bit field as
+SO_TIMESTAMPING. However, only the SOF_TIMESTAMPING_SYS_HARDWARE
+and SOF_TIMESTAMPING_RAW_HARDWARE values are recognized by
+PACKET_TIMESTAMP. SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over
+SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.
+
+ int req = 0;
+ req |= SOF_TIMESTAMPING_SYS_HARDWARE;
+ setsockopt(fd, SOL_PACKET, PACKET_TIMESTAMP, (void *) &req, sizeof(req))
+
+If PACKET_TIMESTAMP is not set, a software timestamp generated inside
+the networking stack is used (the behavior before this setting was added).
+
+See include/linux/net_tstamp.h and Documentation/networking/timestamping
+for more information on hardware timestamps.
+
--------------------------------------------------------------------------------
+ THANKS
--------------------------------------------------------------------------------