...oops... ...forgot to post this to the mailing list... On 10 Dec 2017 at 19:20, Richard Cochran wrote: > Just use > > tcpdump \ > -j adapter_unsynced \ > > > > > --time-stamp-precision=nano \ > > > > > ... other options > I've read 'man pcap-tstamp' to see what -j adapter_unsynced means. "High-precision timestamp, not synchronized to the operating system's
clock". If I provide an UTC-synchronous PPS externally (from a GPS receiver), to maybe 4 ports of i210, how do I reference that precise timestamp to UTC "time of day" when analyzing a resulting PCAP file ? By the time of last modification of the file? Or do the four separate PHC's get synchronized to UTC somehow automagically? The PCAP file normally seems to have an initial absolute timestamp in the header, consequently Wireshark can show absolute UTC-referenced timestamps per packet if asked to... Will it work like that with adapter_unsynced ? > TL;DR the rest... > TL, admittedly, yes :-) > Just get the i210 adapter. The newer ones I've seen already have the > header. > That's my conclusion too. I'm still wondering if all this is useable for *fiber* tapping / capturing. When speaking about the i210, so far it was in the context of 1000Base-TX (or 10/100/1000) i.e. the built-in PHY. The i210 has another SKU that can directly drive a dumb SERDES transceiver (at 1Gb rate) or can talk to an intelligent external PHY via SGMII. Hence my uncertainty: Is the HW timestamping support dependent on the internal metallic PHY, or does it work with an external SGMII-based fiber PHY as well? I've actually found an off-the-shelf NIC with the i210 and an SFP slot: http://www.delock.de/produkte/G_89481/merkmale.html?setLanguage=en For my "application", I've noticed that there are 100Base-FX SFP transceivers with SGMII interface which would make it feasible to grab 100 Mbit fiber optic traffic using an i210. And, apparently, chances are that they are compatible with the i210: https://embedded.communities.intel.com/thread/8856 > > So... looking at the proggie from Mr. Cochran, > > to configure the PHC in a NIC chip to be a PPS slave, > > using a particular SDP pin as an input, I need to open its respective > > /dev/phcX and run some fine-tipped ioctl()s on the open fd. > > Just use the program I posted. > > Or use the 'testptp' program from the Linux kernel. It can configure > the pins via command line. > coool. Thanks for those pointers :-) Frank Rysanek
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