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 5B3A6C4332B for ; Sun, 14 Mar 2021 10:13:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3AE7B64EC8 for ; Sun, 14 Mar 2021 10:13:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235164AbhCNKE1 (ORCPT ); Sun, 14 Mar 2021 06:04:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:55964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235029AbhCNKEW (ORCPT ); Sun, 14 Mar 2021 06:04:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 72A5B64EC6; Sun, 14 Mar 2021 10:04:21 +0000 (UTC) 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: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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