On Thu, May 18, 2017 at 03:38:30PM -0400, Willem de Bruijn wrote: > On Thu, May 18, 2017 at 10:07 AM, Miroslav Lichvar <mlich...@redhat.com> > wrote: > > +Note that if the SO_TIMESTAMP or SO_TIMESTAMPNS option is enabled > > +together with SO_TIMESTAMPING using SOF_TIMESTAMPING_SOFTWARE, a false > > +software timestamp will be generated in the recvmsg() call and passed > > +in ts[0] when a real software timestamp is missing. > > With receive software timestamping this is expected behavior? I would make > explicit that this happens even on tx timestamps.
How about adding ", e.g. when receive timestamping is enabled between receiving the message and the recvmsg() call, or it is a message with a hardware transmit timestamp." ? > > For this reason it > > +is not recommended to combine SO_TIMESTAMP(NS) with SO_TIMESTAMPING. > > And I'd remove this. The extra timestamp is harmless, and we may be missing > other reasons why someone would want to enable both on the same socket. Ok. I'm just concerned people will inadvertently use the timestamp as a real timestamp and then wonder why SW TX timestamping is so bad. I have fallen into this trap. -- Miroslav Lichvar
