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Date:   Thu, 19 Mar 2020 08:55:28 +0200
From:   Leon Romanovsky <leon@kernel.org>
To:     Dimitris Dimitropoulos <d.dimitropoulos@imatrex.com>
Cc:     linux-rdma@vger.kernel.org
Subject: Re: RoCE v2 packet size
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On Wed, Mar 18, 2020 at 03:57:33PM -0700, Dimitris Dimitropoulos wrote:
> Hi,
>
> In RoCE v2 there various options for the protocol packet size: 4096,
> 2048, etc. To what does this number refer to exactly. Is it the
> payload that ends up in the QP buffers, or does it include headers
> some of the headers as well ?

If I'm looking on the correct RoCE spec section (A17.3.1.2.3 PAYLOAD LENGTH).
It doesn't include headers but does include ICRC.

The section "5.2.13 PAYLOAD" in the IBTA spec says that:
"C5-8: All packets of an IBA message that contain a payload shall fill the
payload to the full path MTU except the last (or only) packet of the message."

This is why headers aren't included.

Thanks

>
> Thank you.
>
> Dimitris