path: root/Documentation/networking/packet_mmap.txt
diff options
Diffstat (limited to 'Documentation/networking/packet_mmap.txt')
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/networking/packet_mmap.txt b/Documentation/networking/packet_mmap.txt
index 23dd80e82b8..0f4376ec885 100644
--- a/Documentation/networking/packet_mmap.txt
+++ b/Documentation/networking/packet_mmap.txt
@@ -123,6 +123,16 @@ Transmission process is similar to capture as shown below.
[shutdown] close() --------> destruction of the transmission socket and
deallocation of all associated resources.
+Socket creation and destruction is also straight forward, and is done
+the same way as in capturing described in the previous paragraph:
+ int fd = socket(PF_PACKET, mode, 0);
+The protocol can optionally be 0 in case we only want to transmit
+via this socket, which avoids an expensive call to packet_rcv().
+In this case, you also need to bind(2) the TX_RING with sll_protocol = 0
+set. Otherwise, htons(ETH_P_ALL) or any other protocol, for example.
Binding the socket to your network interface is mandatory (with zero copy) to
know the header size of frames used in the circular buffer.