> On 13 Mar 2023, at 20:35, Richard Cochran <richardcoch...@gmail.com> wrote:
>
> "It works for me" is not a strong argument. This software stack must
> work for everyone.
>
I agree that “It works for me” is not enough to merge this patch.
> Time stamping on top of a bridge interface won't
> fly in general, if I'm not mistaken.
Can you explain the problems you see with timestamping in the interface on top
of a bridge?
From my point of view when you call setsockopt(.., SO_TIMESTAMP**,
SOF_TIMESTAMPING_**_HARDWARE) it does not matter if any network card on your
system support hw timestamping capabilities. At this point network card only
record all socket option values to the socket structure:
https://elixir.bootlin.com/linux/latest/source/net/core/sock.c#L895
<https://elixir.bootlin.com/linux/latest/source/net/core/sock.c#L895>. Next
during package send we check if socket have appropriate timestamping flags, and
if so we copy this info to the sk_buff structure:
https://elixir.bootlin.com/linux/latest/source/include/net/sock.h#L2768
<https://elixir.bootlin.com/linux/latest/source/include/net/sock.h#L2768>. At
the end after package finally ready to be send in ndo_start_xmit
https://elixir.bootlin.com/linux/latest/source/include/linux/netdevice.h#L1401
<https://elixir.bootlin.com/linux/latest/source/include/linux/netdevice.h#L1401>
we either implement required times taping features or not. For example igb
driver checks if tx_flags in skb_buf have timestamping request
https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/intel/igb/igb_main.c#L6432
<https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/intel/igb/igb_main.c#L6432>
and ask hardware to timestamp frame.
So I think that it doesn’t matter how complex your network configuration, only
think that matters is which network card will actually handle frames.
But I’m neither linux kernel networking expert nor PTP expert. If I’m wrong
please correct me.
Regards,
Zaripov Kamil
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