On 3/22/2021 8:40 AM, Miroslav Lichvar wrote:
> FWIW, some onboard NICs supported by the e1000e driver can
> "cross-timestamp" using the Always Running Timer (ART), which should
> avoid the asymmetry of PCIe. I have not seen any detailed description
> of how it actually works.
>
I'm not sure in the e1000e case but in general this is done via PCIe
Precision Time Measurement extension which allows an end-point device
that supports the function to setup a transaction that captures the
device clock and ART value near-simultaneously.
I think the e1000e support might be a variation of this which pre-dated
the PTM standard and works when the device is a LAN-on-motherboard.
_______________________________________________
Linuxptp-devel mailing list
Linuxptp-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
