From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F08AC4361A for ; Fri, 4 Dec 2020 22:21:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2559C22CB9 for ; Fri, 4 Dec 2020 22:21:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726028AbgLDWUt (ORCPT ); Fri, 4 Dec 2020 17:20:49 -0500 Received: from www62.your-server.de ([213.133.104.62]:36586 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725885AbgLDWUt (ORCPT ); Fri, 4 Dec 2020 17:20:49 -0500 Received: from sslproxy01.your-server.de ([78.46.139.224]) by www62.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92.3) (envelope-from ) id 1klJQi-0000Ap-GR; Fri, 04 Dec 2020 23:19:56 +0100 Received: from [85.7.101.30] (helo=pc-9.home) by sslproxy01.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1klJQi-000WQ1-4q; Fri, 04 Dec 2020 23:19:56 +0100 Subject: Re: [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set To: =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= , Maciej Fijalkowski Cc: alardam@gmail.com, magnus.karlsson@intel.com, bjorn.topel@intel.com, andrii.nakryiko@gmail.com, kuba@kernel.org, ast@kernel.org, netdev@vger.kernel.org, davem@davemloft.net, john.fastabend@gmail.com, hawk@kernel.org, jonathan.lemon@gmail.com, bpf@vger.kernel.org, jeffrey.t.kirsher@intel.com, maciejromanfijalkowski@gmail.com, intel-wired-lan@lists.osuosl.org, Marek Majtyka , Jesper Dangaard Brouer References: <20201204102901.109709-1-marekx.majtyka@intel.com> <20201204102901.109709-2-marekx.majtyka@intel.com> <878sad933c.fsf@toke.dk> <20201204124618.GA23696@ranger.igk.intel.com> <048bd986-2e05-ee5b-2c03-cd8c473f6636@iogearbox.net> <87pn3p7aiv.fsf@toke.dk> From: Daniel Borkmann Message-ID: Date: Fri, 4 Dec 2020 23:19:55 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <87pn3p7aiv.fsf@toke.dk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.102.4/26007/Thu Dec 3 14:13:31 2020) Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 12/4/20 6:20 PM, Toke Høiland-Jørgensen wrote: > Daniel Borkmann writes: [...] >> We tried to standardize on a minimum guaranteed amount, but unfortunately not >> everyone seems to implement it, but I think it would be very useful to query >> this from application side, for example, consider that an app inserts a BPF >> prog at XDP doing custom encap shortly before XDP_TX so it would be useful to >> know which of the different encaps it implements are realistically possible on >> the underlying XDP supported dev. > > How many distinct values are there in reality? Enough to express this in > a few flags (XDP_HEADROOM_128, XDP_HEADROOM_192, etc?), or does it need > an additional field to get the exact value? If we implement the latter > we also run the risk of people actually implementing all sorts of weird > values, whereas if we constrain it to a few distinct values it's easier > to push back against adding new values (as it'll be obvious from the > addition of new flags). It's not everywhere straight forward to determine unfortunately, see also [0,1] as some data points where Jesper looked into in the past, so in some cases it might differ depending on the build/runtime config.. [0] https://lore.kernel.org/bpf/158945314698.97035.5286827951225578467.stgit@firesoul/ [1] https://lore.kernel.org/bpf/158945346494.97035.12809400414566061815.stgit@firesoul/ From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Date: Fri, 4 Dec 2020 23:19:55 +0100 Subject: [Intel-wired-lan] [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set In-Reply-To: <87pn3p7aiv.fsf@toke.dk> References: <20201204102901.109709-1-marekx.majtyka@intel.com> <20201204102901.109709-2-marekx.majtyka@intel.com> <878sad933c.fsf@toke.dk> <20201204124618.GA23696@ranger.igk.intel.com> <048bd986-2e05-ee5b-2c03-cd8c473f6636@iogearbox.net> <87pn3p7aiv.fsf@toke.dk> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On 12/4/20 6:20 PM, Toke H?iland-J?rgensen wrote: > Daniel Borkmann writes: [...] >> We tried to standardize on a minimum guaranteed amount, but unfortunately not >> everyone seems to implement it, but I think it would be very useful to query >> this from application side, for example, consider that an app inserts a BPF >> prog at XDP doing custom encap shortly before XDP_TX so it would be useful to >> know which of the different encaps it implements are realistically possible on >> the underlying XDP supported dev. > > How many distinct values are there in reality? Enough to express this in > a few flags (XDP_HEADROOM_128, XDP_HEADROOM_192, etc?), or does it need > an additional field to get the exact value? If we implement the latter > we also run the risk of people actually implementing all sorts of weird > values, whereas if we constrain it to a few distinct values it's easier > to push back against adding new values (as it'll be obvious from the > addition of new flags). It's not everywhere straight forward to determine unfortunately, see also [0,1] as some data points where Jesper looked into in the past, so in some cases it might differ depending on the build/runtime config.. [0] https://lore.kernel.org/bpf/158945314698.97035.5286827951225578467.stgit at firesoul/ [1] https://lore.kernel.org/bpf/158945346494.97035.12809400414566061815.stgit at firesoul/