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Date: Fri, 26 Sep 2025 17:35:39 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: Lorenzo Bianconi <lorenzo@kernel.org>, Donald Hunter
 <donald.hunter@gmail.com>, "David S. Miller" <davem@davemloft.net>, Eric
 Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Simon
 Horman <horms@kernel.org>, Alexei Starovoitov <ast@kernel.org>, Daniel
 Borkmann <daniel@iogearbox.net>, John Fastabend <john.fastabend@gmail.com>,
 Stanislav Fomichev <sdf@fomichev.me>, Andrew Lunn <andrew+netdev@lunn.ch>,
 Tony Nguyen <anthony.l.nguyen@intel.com>, Przemek Kitszel
 <przemyslaw.kitszel@intel.com>, Alexander Lobakin
 <aleksander.lobakin@intel.com>, Andrii Nakryiko <andrii@kernel.org>, Martin
 KaFai Lau <martin.lau@linux.dev>, Eduard Zingerman <eddyz87@gmail.com>,
 Song Liu <song@kernel.org>, Yonghong Song <yonghong.song@linux.dev>, KP
 Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>, Jiri Olsa
 <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>, Maciej Fijalkowski
 <maciej.fijalkowski@intel.com>, netdev@vger.kernel.org,
 bpf@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
 linux-kselftest@vger.kernel.org
Subject: Re: [PATCH RFC bpf-next v2 1/5] netlink: specs: Add XDP RX checksum
 capability to XDP metadata specs
Message-ID: <20250926173539.17403e94@kernel.org>
In-Reply-To: <0608935c-1c1c-4374-a058-bc78d114c630@kernel.org>
References: <20250925-bpf-xdp-meta-rxcksum-v2-0-6b3fe987ce91@kernel.org>
	<20250925-bpf-xdp-meta-rxcksum-v2-1-6b3fe987ce91@kernel.org>
	<0608935c-1c1c-4374-a058-bc78d114c630@kernel.org>
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On Fri, 26 Sep 2025 11:53:25 +0200 Jesper Dangaard Brouer wrote:
> > + * In case of success, ``cksum_meta`` contains the hw computed checksum value
> > + * for ``XDP_CHECKSUM_COMPLETE`` or the ``csum_level`` for
> > + * ``XDP_CHECKSUM_UNNECESSARY``. It is set to 0 for ``XDP_CHECKSUM_NONE`` and
> > + * ``XDP_CHECKSUM_PARTIAL``.
> > + *  
> 
> It is very important that we explain the meaning of XDP_CHECKSUM_NONE.
> As I hinted in other email, this also covers the non-existing FAIL case.

Good idea, perhaps we should add this to the big comment about
checksums in skbuff.h and point to that? Avoid the duplication?