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Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , Andrew Lunn , Tony Nguyen , Przemek Kitszel , Alexander Lobakin , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , Shuah Khan , Maciej Fijalkowski , netdev@vger.kernel.org, bpf@vger.kernel.org, intel-wired-lan@lists.osuosl.org, linux-kselftest@vger.kernel.org In-Reply-To: (Lorenzo Bianconi's message of "Thu, 25 Sep 2025 12:39:22 +0200") References: <20250925-bpf-xdp-meta-rxcksum-v2-0-6b3fe987ce91@kernel.org> <87bjmy508n.fsf@cloudflare.com> Date: Thu, 25 Sep 2025 12:58:14 +0200 Message-ID: <87tt0q3ik9.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain X-Mailman-Approved-At: Thu, 25 Sep 2025 15:11:15 +0000 X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google09082023; t=1758797896; x=1759402696; darn=lists.osuosl.org; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:from:to:cc:subject:date:message-id:reply-to; bh=qoutmRJfBiooSSHCtQV7QJz0oS7nanw5QS3919xibtc=; b=eTxDK+VYlO64p7/TaSKJUywH6Ti7iAIpGJxXlVkae7I2T9lGRNj7CQJbflZ3x8NREo oyTXkG68h7nFzcfvOJJwyyFeIdamwkO5W98LUbDX+LNWEZdCHx7vq4l7XxfxRY18Kk5w n/DGHjO7WmvjO4itThIYWlqt+/zCCFSM4Fi7enipt48aiUg9FQVUmaE0J0DqnlBpC4NK bgocrP8eSXfrPD3KnGhZ23xUqGMbz1f7jEOTfoJ0SqHUFOcJpe66mGXC9Ar007Q135BU oBfVNL+4QcB4HLX0SlmtWzjS8ADmXu/2ISmEzSVYfVYvreeeYqdnAxgVxHTIfD2xCEl0 JYNQ== X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dmarc=pass (p=reject dis=none) header.from=cloudflare.com X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=cloudflare.com header.i=@cloudflare.com header.a=rsa-sha256 header.s=google09082023 header.b=eTxDK+VY Subject: Re: [Intel-wired-lan] [PATCH RFC bpf-next v2 0/5] Add the the capability to load HW RX checsum in eBPF programs X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" On Thu, Sep 25, 2025 at 12:39 PM +02, Lorenzo Bianconi wrote: >> On Thu, Sep 25, 2025 at 11:30 AM +02, Lorenzo Bianconi wrote: >> > Introduce bpf_xdp_metadata_rx_checksum() kfunc in order to load the HW >> > RX cheksum results in the eBPF program binded to the NIC. >> > Implement xmo_rx_checksum callback for veth and ice drivers. >> >> What are going to do with HW RX checksum once XDP prog can access it? > > I guess there are multiple use-cases for bpf_xdp_metadata_rx_checksum() > kfunc. The first the I have in mind is when packets are received by an af_xdp > application. In this case I think we currently do not have any way to check if > the packet checksum is correct, right? > I think Jesper has other use-cases in mind, I will let him comment > here. Can you share more details on what the AF_XDP application would that info? Regarding the use cases that Jesper is trying to unlock, as things stand we don't have a way, or an agreement on how to inject/propagate even the already existing NIC hints back into the network stack. Hence my question - why do we want to expose another NIC hint to XDP that we can't consume in any useful way yet? Shouldn't we first figure out how we're planning to re-inject that info into the stack?