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 17AC0C433DB for ; Mon, 22 Mar 2021 05:39:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D7D3161967 for ; Mon, 22 Mar 2021 05:39:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229822AbhCVFjZ (ORCPT ); Mon, 22 Mar 2021 01:39:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:46614 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229621AbhCVFjP (ORCPT ); Mon, 22 Mar 2021 01:39:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 69882601FE; Mon, 22 Mar 2021 05:39:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616391555; bh=wtAYmmg5bTmlX11026gT4vxnsv9pHiDO0GoAP4cPjN0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Xp3IMm9BgBDPBrOU1gWtYBz1KmnBjDWnIdISWcsoy2IrleEvHTAPJbAheSq5/Vx/R p7+dSW+ZKB82D5dxUnKt64B+vMhMxTKWfnRzpqMwuxvxVpZ4DupgF2GjPAflm5tDxU njaKmhxIc0qnlPFFGKPCqHwdJ2EHy9f9D/R4OYYrm3Y1m0C0H8I9ngJKXSB5DvU7sF pAEsY6pNUJFrwksSP7ZWcfa6E/pSIFskPZ9I7AhtB1XpDr7+q+IxrfWNKvKFTgtyFY I/9dYM98IvxgM7zcDu5L6PARQcTCOjXj/s0xsVBfBIpQSoc5WV/hOG9gz054d0YytQ 22szeX2q8CKUA== Date: Mon, 22 Mar 2021 07:39:11 +0200 From: Leon Romanovsky To: "Hsu, Chiahao" Cc: Andrew Lunn , netdev@vger.kernel.org, wei.liu@kernel.org, paul@xen.org, davem@davemloft.net, kuba@kernel.org, xen-devel@lists.xenproject.org Subject: Re: [net-next 1/2] xen-netback: add module parameter to disable ctrl-ring Message-ID: References: <20210311225944.24198-1-andyhsu@amazon.com> <64f5c7a8-cc09-3a7f-b33b-a64d373aed60@amazon.com> <12f643b5-7a35-d960-9b1f-22853aea4b4c@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <12f643b5-7a35-d960-9b1f-22853aea4b4c@amazon.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, Mar 21, 2021 at 06:54:52PM +0100, Hsu, Chiahao wrote: > <...> > > > Typically there should be one VM running netback on each host, > > > and having control over what interfaces or features it exposes is also > > > important for stability. > > > How about we create a 'feature flags' modparam, each bits is specified for > > > different new features? > > At the end, it will be more granular module parameter that user still > > will need to guess. > I believe users always need to know any parameter or any tool's flag before > they use it. > For example, before user try to set/clear this ctrl_ring_enabled, they > should already have basic knowledge about this feature, > or else they shouldn't use it (the default value is same as before), and > that's also why we use the 'ctrl_ring_enabled' as parameter name. It solves only forward migration flow. Move from machine A with no option X to machine B with option X. It doesn't work for backward flow. Move from machine B to A back will probably break. In your flow, you want that users will set all module parameters for every upgrade and keep those parameters differently per-version. Thanks > > Thanks > > Thanks > > >