> -----Original Message-----
> From: Yan Yankovskyi via Linuxptp-users [mailto:linuxptp-
> us...@lists.sourceforge.net]
> Sent: Thursday, February 08, 2018 5:40 AM
> To: Richard Cochran <richardcoch...@gmail.com>
> Cc: linuxptp-us...@lists.sourceforge.net
> Subject: Re: [Linuxptp-users] Bad message error
> > The topic was running PTP over a VLAN
> > interface.  This is now fully supported by the Linux kernel.
> Even in kernel version 4.15.2 in file net/8021q/vlan_dev.c function
> vlan_ethtool_get_ts_info contains the following code:
> info->so_timestamping = SOF_TIMESTAMPING_RX_SOFTWARE |
> And it seems that absence of SOF_TIMESTAMPING_TX_SOFTWARE flag
> in this place is leading to fail in ethtool check. Is adding the flag in this 
> function
> is all I need to do to implement this functionality? It seems like it isn't, 
> but I'm not
> sure. Don't you know any manual I could refer?

Your network driver has to support software timestamping via sk_timestamp_tx() 
call in its Tx routine in order for software Tx timestamps to work. VLAN 
forwards the frame to the lowerdev so it likely doesn't advertise Tx timestamp 
support because not all lowerdevs support it.

Note that the VLAN driver only returns these values if the lowerdev doesn't 
have a get_ts_info, so you likely need to implement the get_ts_info op for the 
driver you're running in order to correctly enable this behavior.

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