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From: Jesper Dangaard Brouer <>
To: Kurt Kanzenbach <>
Cc:, Jesse Brandeburg <>,
	Tony Nguyen <>,
	"David S. Miller" <>,
	Jakub Kicinski <>,
	Alexei Starovoitov <>,
	Daniel Borkmann <>,
	Jesper Dangaard Brouer <>,
	John Fastabend <>,
	Sven Auhagen <>,,,,
	Ilias Apalodimas <>,
	Lorenzo Bianconi <>,
	Sebastian Andrzej Siewior <>,
	Richard Cochran <>,
	Alexander Duyck <>,
	Tyler S <>,
	Maciej Fijalkowski <>
Subject: Re: [PATCH net v4] igb: Fix XDP with PTP enabled
Date: Tue, 4 May 2021 10:28:27 +0200
Message-ID: <20210504102827.342f6302@carbon> (raw)
In-Reply-To: <>

On Mon,  3 May 2021 09:28:00 +0200
Kurt Kanzenbach <> wrote:

> When using native XDP with the igb driver, the XDP frame data doesn't point to
> the beginning of the packet. It's off by 16 bytes. Everything works as expected
> with XDP skb mode.
> Actually these 16 bytes are used to store the packet timestamps. Therefore, pull
> the timestamp before executing any XDP operations and adjust all other code
> accordingly. The igc driver does it like that as well.
> Tested with Intel i210 card and AF_XDP sockets.
> Fixes: 9cbc948b5a20 ("igb: add XDP support")
> Signed-off-by: Kurt Kanzenbach <>

Thanks for fixing this!

Acked-by: Jesper Dangaard Brouer <>

I expect that we/I will (soon) play with getting this area that is
stored in front of the packet (the XDP data_meta area) described via
BTF.  This way both xdp_frame and AF_XDP can get structured access (e.g.
to the PTP timestamp in this case).

I'll be adding my notes on this project here:

Looking forward to collaborate on this with you :-)
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat

  reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-03  7:28 Kurt Kanzenbach
2021-05-04  8:28 ` Jesper Dangaard Brouer [this message]
2021-05-19 13:34   ` Jesper Dangaard Brouer
2021-05-19 18:46     ` Nguyen, Anthony L
2021-05-20  6:20       ` Kurt Kanzenbach
2021-06-03 11:30 ` Penigalapati, Sandeep

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