feature: add hardware RX timestamp support

Question

feature: add hardware RX timestamp support

ddrown opened this issue 4 years ago · 6 comments

Right now, this code is using SO_TIMESTAMPNS/SO_TIMESTAMP, which use kernel level RX timestamps. The documentation and code comment state "hardware timestamps", which is misleading. These timestamps come from https://elixir.bootlin.com/linux/latest/C/ident/net_timestamp_check while "hardware timestamps" would come from 1588 timer hardware in the NIC itself.

https://www.kernel.org/doc/Documentation/networking/timestamping.txt has documentation on the SO_TIMESTAMPING flag, which accepts SOF_TIMESTAMPING_RX_HARDWARE. NIC 1588 hardware timers are usually not synchronized to system time, so your software would need to do that as well. chrony has an example of all of this.

This is just the RX timestamps. TX timestamps could be enabled in NTP interleaved mode, but that would mean keeping state per client. I'm assuming keeping state per client would conflict with the other goals of this project.

Answer 1 · 2020-07-07T10:26:21.000Z

Thanks for reporting it!

Answer 2 · 2020-07-28T11:50:56.000Z

I think it is better to leave this open in case we want to add HW timestamps.

Answer 3 · 2023-09-04T09:19:21.000Z

#76 Is related to this issue. The PTP server is making use of the HW timestamps.

Answer 4 · 2024-04-20T06:22:43.000Z

I think this can be closed after #346

Answer 5 · 2024-04-20T08:13:42.000Z

@pmazzini I wanted to close it on Monday once we release the rpms.

Answer 6 · 2024-05-01T11:51:56.000Z

RPMs are released, feature is working in prod. Closing.