linux-kernel - Re: [PATCH bpf-next,v4 1/1] doc: clarify XDP Rx metadata handling and driver requirements

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Message-ID: <20250715164913.3ed08273@kernel.org>
Date: Tue, 15 Jul 2025 16:49:13 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Song Yoong Siang <yoong.siang.song@...el.com>
Cc: "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Simon Horman
 <horms@...nel.org>, Jonathan Corbet <corbet@....net>, Alexei Starovoitov
 <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Jesper Dangaard
 Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>,
 Stanislav Fomichev <sdf@...ichev.me>, netdev@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next,v4 1/1] doc: clarify XDP Rx metadata handling
 and driver requirements

On Tue, 15 Jul 2025 15:15:02 +0800 Song Yoong Siang wrote:
> -An XDP program can store individual metadata items into this ``data_meta``
> +Certain devices may utilize the ``data_meta`` area for specific purposes.

Calling headroom "``data_meta`` area" is confusing, IMO. I'd say:

  Certain devices may prepend metadata to received packets.

And the rest of this paragraph can stay as is.

> +Drivers for these devices must move any hardware-related metadata out from the
> +``data_meta`` area before presenting the frame to the XDP program. This ensures
> +that the XDP program can store individual metadata items into this ``data_meta``