From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from nyc.source.kernel.org (nyc.source.kernel.org [IPv6:2604:1380:45d1:ec00::3]) by mail.toke.dk (Postfix) with ESMTPS id 5F56DAE08E1 for ; Mon, 27 Jan 2025 19:04:46 +0100 (CET) Authentication-Results: mail.toke.dk; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=pa1i/Uqj Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id DDDC1A4195C; Mon, 27 Jan 2025 18:02:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F93BC4CED2; Mon, 27 Jan 2025 18:04:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738001084; bh=H/TAc9fGLArvc2BRtJuDGahSmYMiOfZlb3sEWjWRvdk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=pa1i/Uqj8nt3XnOgB4es4hq3WXqmWYJe+K+7Ypr1PhtZKUOMb+h3wCHGV8pGfCXWf V/jNdW1KJ0DAgBElQtp27kbynF6Xdb64ebEeDtcaavOt9nt3wH1DLI4Alev/ln14Z5 8MnTCYVHpwTy5t3/GnzlRYIwYejiGooeUjDn1YgpVCFKG0fB11N85ZNFumQQbSP2kU WigdIP+MK+4Ziy2Bpk1ilyK4PIrxFTjdf+y0w2rgNqfwu0cfUToiNhOhF8q3sAM18+ xPG+JfYTyHktRw2Gk07i3VSNMzu5ZS6RERP5ylIMJESoE+MWfyQ7kbBA6E5MKHoZY2 EGi/oAiz8W3jA== Date: Mon, 27 Jan 2025 10:04:41 -0800 From: Jakub Kicinski To: Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?= Message-ID: <20250127100441.0b11e1b8@kernel.org> In-Reply-To: <87bjvwqvtl.fsf@toke.dk> References: <20250116155350.555374-1-yoong.siang.song@intel.com> <20250116155350.555374-5-yoong.siang.song@intel.com> <87bjvwqvtl.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Message-ID-Hash: 4D7WUMNHD6IRVECPCM6OAHQ2YJWDERVI X-Message-ID-Hash: 4D7WUMNHD6IRVECPCM6OAHQ2YJWDERVI X-MailFrom: kuba@kernel.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Stanislav Fomichev , Florian Bezdeka , "Song, Yoong Siang" , "Bouska, Zdenek" , "David S . Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Willem de Bruijn , Donald Hunter , Jonathan Corbet , Bjorn Topel , "Karlsson, Magnus" , "Fijalkowski, Maciej" , Jonathan Lemon , Andrew Lunn , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , "Damato, Joe" , Stanislav Fomichev , Xuan Zhuo , Mina Almasry , Daniel Jurgens , Andrii Nakryiko , Eduard Zingerman , Mykola Lysenko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , Shuah Khan , Alexandre Torgue , Jose Abreu , Maxime Coquelin , "Nguyen, Anthony L" , "Kitszel, Przemyslaw" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , "linux-arm-kernel@lists.infradead.org" , "intel-wired-lan@lists.osuosl.org" , "xdp-hints@xdp-project.net" X-Mailman-Version: 3.3.10 Precedence: list Subject: [xdp-hints] Re: [PATCH bpf-next v6 4/4] igc: Add launch time support to XDP ZC List-Id: XDP hardware hints design discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Fri, 24 Jan 2025 12:45:42 +0100 Toke H=C3=B8iland-J=C3=B8rgensen wrote: > >> I think there is no simple fix for that. That needs some discussion > >> around the "expectations" to the headroom / meta data area in front of > >> the actual packet data. =20 > > > > By 'simple' you mean without some new UAPI to signal the size of that > > 'reserved area' by the driver? I don't see any other easy way out as we= ll :-/ =20 >=20 > Yeah, I don't think we can impose UAPI restrictions on the metadata area > at this point. I guess the best we can do is to educate users that they > should call the timestamp kfunc before they modify the metadata? I may be misunderstanding the discussion, but I think the answer=20 is that the driver must be fixed. The metadata-in-prepend problem also exists for simple adjust head use case, so it existed since early days of BPF. The driver should copy out (or parse) the metadata before it invokes the XDP prog. The nfp driver does that.