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 842FAC433DB for ; Sun, 14 Mar 2021 10:04:52 +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 325C964EBD for ; Sun, 14 Mar 2021 10:04:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 325C964EBD 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.97688.185461 (Exim 4.92) (envelope-from ) id 1lLNbk-0007fK-QZ; Sun, 14 Mar 2021 10:04:24 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 97688.185461; Sun, 14 Mar 2021 10:04:24 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lLNbk-0007fD-Lz; Sun, 14 Mar 2021 10:04:24 +0000 Received: by outflank-mailman (input) for mailman id 97688; Sun, 14 Mar 2021 10:04:24 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lLNbk-0007f8-11 for xen-devel@lists.xenproject.org; Sun, 14 Mar 2021 10:04:24 +0000 Received: from mail.kernel.org (unknown [198.145.29.99]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 0142cc59-12d2-488e-a6a1-fc18e208b0f4; Sun, 14 Mar 2021 10:04:22 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 72A5B64EC6; Sun, 14 Mar 2021 10:04:21 +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: 0142cc59-12d2-488e-a6a1-fc18e208b0f4 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615716262; bh=YaBvDkHUpVHgz7IeG1nFxa4iaw8l+effxELbw6xjnSE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f9YaaxkaUJC+S1azF/+EVhOe/Lsd3o7jbq4JOjr3/2DQ6MhgN9b59MDqcefZZsdKg 6jP871VcuNH1rT616IsxvMjOXZbZC6tFGVQB7r9KoIyJusI40pMgHxlaHBROWaZkBt cXn7MylmRqRpBsgDR40EfziTbjSNq4a+kNLjoZsEYGUn1KqLLj8YGINoZ6QPQpSng0 xCvyfxE2aTO2draiJuQtp2Qo08K303pVPUmIOsKjqaL953lovzlHLAc+poc6yHQz96 PnQ+52gWBxkJ+p7IoX8p1gGCUelyP2/7a2SsDQFdStJ2v+mIkD0Eip6flduJgjCcRz DY4pge6ieA9cQ== Date: Sun, 14 Mar 2021 12:04:18 +0200 From: Leon Romanovsky To: Andrew Lunn Cc: "Hsu, Chiahao" , 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Mar 12, 2021 at 09:36:59PM +0100, Andrew Lunn wrote: > On Fri, Mar 12, 2021 at 04:18:02PM +0100, Hsu, Chiahao wrote: > > > > Andrew Lunn 於 2021/3/12 15:52 寫道: > > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. > > > > > > > > > > > > On Thu, Mar 11, 2021 at 10:59:44PM +0000, ChiaHao Hsu wrote: > > > > In order to support live migration of guests between kernels > > > > that do and do not support 'feature-ctrl-ring', we add a > > > > module parameter that allows the feature to be disabled > > > > at run time, instead of using hardcode value. > > > > The default value is enable. > > > Hi ChiaHao > > > > > > There is a general dislike for module parameters. What other mechanisms > > > have you looked at? Would an ethtool private flag work? > > > > > > Andrew > > > > > > Hi Andrew, > > > > I can survey other mechanisms, however before I start doing that, > > > > could you share more details about what the problem is with using module > > parameters? thanks. > > It is not very user friendly. No two kernel modules use the same > module parameters. Often you see the same name, but different > meaning. There is poor documentation, you often need to read the > kernel sources it figure out what it does, etc. +1, It is also global parameter to whole system/devices that use this module, which is rarely what users want. Thanks