On Tue, Feb 07, 2017 at 12:37:15PM -0800, sdncurious wrote: > On Tue, Feb 7, 2017 at 6:01 AM, Miroslav Lichvar <mlich...@redhat.com> wrote: > > 6) new SO_TIMESTAMPING option to get PHC index with HW timestamps > > > > With bridges, bonding and other things it's difficult to determine > > which PHC timestamped the packet. It would be very useful if the > > PHC index was provided with each HW timestamp. > > > > I'm not sure what would be the best place to put it. I guess the > > second timespec in scm_timestamping could be reused for this, but > > that sounds like a gross hack. Do we need to define a new struct? > > What is the use case for this. even if the delay though the PHY's how > would that be compensated ?
The idea was that applications like NTP servers and clients wouldn't have to care about interfaces and how they map together with addresses to PHCs over time. Currently, I use the interface index from IP_PKTINFO to get the PHC, but that doesn't work with bridges and other virtual interfaces. Another possibility would be an option to modify the behavior of IP_PKTINFO to save the index of the real interface. I'm not sure how would that compare in difficulty to extending SCM_TIMESTAMPING with PHC index. -- Miroslav Lichvar
