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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 E693AC433E0 for ; Thu, 14 Jan 2021 02:27:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0A81235FA for ; Thu, 14 Jan 2021 02:27:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726709AbhANC17 (ORCPT ); Wed, 13 Jan 2021 21:27:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:46930 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726011AbhANC16 (ORCPT ); Wed, 13 Jan 2021 21:27:58 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8AF7B235FA; Thu, 14 Jan 2021 02:27:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610591237; bh=9aPLMQ4TAtrEeG1rxut2Ir8PeCXrxvNYRF4299rf+bk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LXtokPdQN+7abJ43w4XhUEOeb/9JpE0ysXXkcdGC4ZfFMFhC7any+KkjnuKiBajyb 2GfnnRsZeRH+iwE/PoZhNkBLPo9VSWNL3tZTokv1KwIs27dRmZQt6eIDjhuzXEK7wj XYTzqarg8UrZIf8P+vXlDhz2V5S1USr4De4ZMtQrM41AfOHvzB0kTQrKlWHXrrXJ19 70OeYnlJX2le18UIMEGnitKpTS5eVo7BwoP4msu7MIyfpV90JWoo+8/IiZnO1JGpsn Z1MLykq5AtwFy1mYe+L7ZzB6J4gdZpz/+Wxl1+rfPdlQeohah88Pw7+6Avg5Qs/8x9 ZVWAAVxfXx5FA== Date: Wed, 13 Jan 2021 18:27:16 -0800 From: Jakub Kicinski To: Jiri Pirko Cc: netdev@vger.kernel.org, davem@davemloft.net, jacob.e.keller@intel.com, roopa@nvidia.com, mlxsw@nvidia.com Subject: Re: [patch net-next RFC 00/10] introduce line card support for modular switch Message-ID: <20210113182716.2b2aa8fa@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <20210113121222.733517-1-jiri@resnulli.us> References: <20210113121222.733517-1-jiri@resnulli.us> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 13 Jan 2021 13:12:12 +0100 Jiri Pirko wrote: > This patchset introduces support for modular switch systems. > NVIDIA Mellanox SN4800 is an example of such. It contains 8 slots > to accomodate line cards. Available line cards include: > 16X 100GbE (QSFP28) > 8X 200GbE (QSFP56) > 4X 400GbE (QSFP-DD) > > Similar to split cabels, it is essencial for the correctness of > configuration and funcionality to treat the line card entities > in the same way, no matter the line card is inserted or not. > Meaning, the netdevice of a line card port cannot just disappear > when line card is removed. Also, system admin needs to be able > to apply configuration on netdevices belonging to line card port > even before the linecard gets inserted. I don't understand why that would be. Please provide reasoning, e.g. what the FW/HW limitation is. > To resolve this, a concept of "provisioning" is introduced. > The user may "provision" certain slot with a line card type. > Driver then creates all instances (devlink ports, netdevices, etc) > related to this line card type. The carrier of netdevices stays down. > Once the line card is inserted and activated, the carrier of the > related netdevices goes up. Dunno what "line card" means for Mellovidia but I don't think the analogy of port splitting works. To my knowledge traditional line cards often carry processors w/ full MACs etc. so I'd say plugging in a line card is much more like plugging in a new NIC. There is no way to tell a breakout cable from normal one, so the system has no chance to magically configure itself. Besides SFP is just plugging a cable, not a module of the system..