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Subject: Re: [PATCH v4 3/6] net/nfb: update timestamp calculation to
 meaningful value
From: Martin Spinler <spinler@cesnet.cz>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: dev@dpdk.org
Date: Tue, 27 Jan 2026 09:12:13 +0100
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On Wed, 2026-01-21 at 09:33 -0800, Stephen Hemminger wrote:
> The patch is ok as far as it goes.
>=20
> But the best practice in DPDK for drivers doing timestamps is for
> the driver to only put a timestamp on if timestamp offload flag
> was set when configuring that device. For the case of multiple devices
> that means that one device may have timestamp and other not.

Ack. I'll work it in.

> Also any driver that supports receive timestamp must provide
> a read_clock operation. Otherwise the application has no way of knowing
> what units the timestamp is in. I added that to the AI review
> script so new drivers will get rejected with out it.

Ack.

> I suspect that in this drivers case it is only used in systems where:
>  - only single instance of device is possible
>  - your application is just assuming a common unit like nanosecond.

You're right.


More responses in another email thread.