> On Jan 18, 2017, at 05:43, Miroslav Lichvar <mlich...@redhat.com> wrote: > Denny, > > there is apparently a new ioctl for measuring the offset between the > NIC clock and system clock, which is supported on some onboard NICs > (that share clock with the CPU?). It's called PTP_SYS_OFFSET_PRECISE > and if I understand how it works correctly, it should solve all these > problems with delay and asymmetry. Is it supported on the i211 or > i350?
Miroslav, Unfortunately, no. PTP_SYS_OFFSET_PRECISE uses PCIE_PTM (Precise Time Measurement) which requires newer PCIe chipsets. I don’t have a system that supports PTM. Best that I can tell, the only Ethernet driver in the kernel that currently offers PTM support is the Intel PCI-Express pro/1000 (E1000E), and I don’t have one of those either. Otherwise I would have added support for it in ethtscal. :) https://pcisig.com/sites/default/files/specification_documents/ECN_PTM_Revision1a_31_Mar_2013.pdf <https://pcisig.com/sites/default/files/specification_documents/ECN_PTM_Revision1a_31_Mar_2013.pdf> Denny