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 B343AC433E0 for ; Mon, 22 Mar 2021 05:39:50 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6804F61966 for ; Mon, 22 Mar 2021 05:39:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6804F61966 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.99981.190298 (Exim 4.92) (envelope-from ) id 1lODHa-0004yg-9Q; Mon, 22 Mar 2021 05:39:18 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 99981.190298; Mon, 22 Mar 2021 05:39:18 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lODHa-0004yZ-5y; Mon, 22 Mar 2021 05:39:18 +0000 Received: by outflank-mailman (input) for mailman id 99981; Mon, 22 Mar 2021 05:39:16 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lODHY-0004y8-Iq for xen-devel@lists.xenproject.org; Mon, 22 Mar 2021 05:39:16 +0000 Received: from mail.kernel.org (unknown [198.145.29.99]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 81c9bebf-19d0-4232-8cea-4e4401c6b5e0; Mon, 22 Mar 2021 05:39:15 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 69882601FE; Mon, 22 Mar 2021 05:39:14 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 81c9bebf-19d0-4232-8cea-4e4401c6b5e0 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> 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 > > >