> Am 10.06.2016 um 00:13 schrieb Guy Harris <g...@alum.mit.edu>: > > But that doesn't mean that the packets time stamped by the hardware when > transmitted will be delivered to the PF_PACKET sockets used by libpcap *with > the hardware time stamp as the time stamp*. > > In order make that happen, if hardware transmit time stamping is enabled for > a PF_PACKET socket: > > dev_queue_xmit_nit() will *NOT* deliver, to that socket, packets queued > for transmission; > > when the hardware says "I've transmitted these packets" (and > time-stamped them), the driver will take those packets and deliver them to > all PF_PACKET sockets with hardware transmit time stamping enabled? > > If those aren't done, then code processing packets from a PF_PACKET socket > will get a mix of packets with software time stamps (packets sent by the > machine on which that code is running) and hardware time stamps (packets > received by that machine). > > I don't see any obvious code in dev_queue_xmit_nit() to avoid delivering > packets to sockets that have requested hardware time stamping, so the first > of those statements doesn't appear to be true; is the second one true?
Perhaps I am wrong, but it seems the drivers deliver the sent packets, including the hardware-timestamp, to the error queue of the socket. They all call skb_tstamp_tx() to do this, after the hardware has transmitted the packet and time-stamped it. _______________________________________________ tcpdump-workers mailing list tcpdump-workers@lists.tcpdump.org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
