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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 2D8A4C433E0 for ; Mon, 18 May 2020 09:50:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1470E20715 for ; Mon, 18 May 2020 09:50:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726448AbgERJub (ORCPT ); Mon, 18 May 2020 05:50:31 -0400 Received: from mx2.suse.de ([195.135.220.15]:57590 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726040AbgERJub (ORCPT ); Mon, 18 May 2020 05:50:31 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 88A57B155; Mon, 18 May 2020 09:50:31 +0000 (UTC) Date: Mon, 18 May 2020 11:50:26 +0200 From: Petr Mladek To: Orson Zhai Cc: Leon Romanovsky , Orson Zhai , Jason Baron , Randy Dunlap , Linux Kernel Mailing List , linux-doc@vger.kernel.org, netdev@vger.kernel.org, linux-rdma@vger.kernel.org, Jonathan Corbet , Sergey Senozhatsky , Steven Rostedt , Greg Kroah-Hartman , "David S . Miller" , Jakub Kicinski , Doug Ledford , Jason Gunthorpe , Andrew Morton , Android Kernel Team , Orson Zhai Subject: Re: [PATCH V2] dynamic_debug: Add an option to enable dynamic debug for modules only Message-ID: <20200518095026.GL7340@linux-b0ei> References: <1587408228-10861-1-git-send-email-orson.unisoc@gmail.com> <20200420191014.GE121146@unreal> <20200422142552.GA492196@unreal> <20200515095501.GU17734@linux-b0ei> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat 2020-05-16 11:55:04, Orson Zhai wrote: > On Fri, May 15, 2020 at 5:55 PM Petr Mladek wrote: > > > > On Thu 2020-04-23 00:02:48, Orson Zhai wrote: > > > On Wed, Apr 22, 2020 at 10:25 PM Leon Romanovsky wrote: > > > > > > > > On Wed, Apr 22, 2020 at 09:06:08PM +0800, Orson Zhai wrote: > > > > > On Tue, Apr 21, 2020 at 3:10 AM Leon Romanovsky wrote: > > > > > My motivation came from the concept of GKI (Generic Kernel Image) in Android. > > > > > Google will release a common kernel image (binary) to all of the Android system > > > > > vendors in the world instead of letting them to build their owns as before. > > > > > Every SoC vendor's device drivers will be provided in kernel modules only. > > > > > By my patch, the driver owners could debug their modules in field (say > > > > > production releases) > > > > > without having to enable dynamic debug for the whole GKI. > > > > > > > > Will Google release that binary with CONFIG_DYNAMIC_DEBUG_CORE disabled? > > > > > > > In Google's plan, there will be only one GKI (no debug version) for > > > one Android version per kernel version per year. > > > > Are there plans to use modules with debug messages enabled on production > > systems? > > Yes, but in a managed way. They are not being enabled directly to log buffer. > Users / FAEs (Field Application Engineer) might control to open or > close every single one on-the-fly. I see. > > IMHO, the debug messages are primary needed during development and > > when fixing bugs. I am sure that developers will want to enable many > > more features that will help with debugging and which will be disabled > > on production systems. > > I agree with you in general speaking. > For real production build we usually keep a few critical debugging > methods in case of some > potential bugs which are extremely hard to be found in production test. > Dynamic debug is one of these methods. > I assume it is widely used for maintenance to PC or server because I > can find it is enabled in some > popular Linux distribution configs. Fair enough. Feel free to add: Acked-by: Petr Mladek Best Regards, Petr