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=-2.2 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 D29A2C43331 for ; Fri, 27 Mar 2020 18:04:28 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 8D77021473 for ; Fri, 27 Mar 2020 18:04:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D77021473 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 64E6B8775C; Fri, 27 Mar 2020 18:04:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id CkCFXGTCYsef; Fri, 27 Mar 2020 18:04:27 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 57A1F8775A; Fri, 27 Mar 2020 18:04:27 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 45751C1D7C; Fri, 27 Mar 2020 18:04:27 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id C2261C0177 for ; Fri, 27 Mar 2020 18:04:25 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id A90DC265AD for ; Fri, 27 Mar 2020 18:04:25 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id auwAkeHbV4vC for ; Fri, 27 Mar 2020 18:04:24 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by silver.osuosl.org (Postfix) with ESMTP id 5A4A5264B4 for ; Fri, 27 Mar 2020 18:04:24 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B1F2730E; Fri, 27 Mar 2020 11:04:23 -0700 (PDT) Received: from [10.57.60.204] (unknown [10.57.60.204]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D425B3F71E; Fri, 27 Mar 2020 11:04:22 -0700 (PDT) Subject: Re: [PATCH] iommu: Lower severity of add/remove device messages To: Ezequiel Garcia , Joerg Roedel References: <20200323214956.30165-1-ezequiel@collabora.com> <20200327095029.GB11538@8bytes.org> <9e863f96cd9a188db84ae8bc5a0d49287b4b4922.camel@collabora.com> From: Robin Murphy Message-ID: <6db3bcfb-c778-7190-a936-836eaba4bb73@arm.com> Date: Fri, 27 Mar 2020 18:04:22 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <9e863f96cd9a188db84ae8bc5a0d49287b4b4922.camel@collabora.com> Content-Language: en-GB Cc: iommu@lists.linux-foundation.org, kernel@collabora.com, linux-kernel@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2020-03-27 1:02 pm, Ezequiel Garcia wrote: > Hello Joerg, > > Thanks for reviewing. > > I understand this change bears some controversy > for IOMMU, as developers are probably used to see these > messages. > > On Fri, 2020-03-27 at 10:50 +0100, Joerg Roedel wrote: >> On Mon, Mar 23, 2020 at 06:49:56PM -0300, Ezequiel Garcia wrote: >>> These user messages are not really informational, >>> but mostly of debug nature. Lower their severity. >> >> Like most other messages in the kernel log, that is not a reason to >> lower the severity. >> >> These messages are the first thing to look at when >> looking into IOMMU related issues. >> > > Sure, but the messages are still here, you can > always enable them when you are looking at IOMMU issues :-) That still begs the question of who "you" is and how they know they're debugging an IOMMU issue in the first place. When all the developer has to go on is a third-hand bugzilla attachment from a distro user's vague report of graphics corruption/poor I/O performance/boot failure/whatever, being able to tell straight away from a standard dmesg dump whether an IOMMU is even in the picture or not saves a lot of protracted back-and-forth for everyone involved. > The idea is to reduce the amount of verbosity in the kernel. Under what justification? Users with slow consoles or who just want a quiet boot are already free to turn down the loglevel; a handful of messages at boot-time and device hotplug seem hardly at risk of drowning out all the systemd audit spam anyway. Note that the IOMMU subsystem is by nature a little atypical as a lot of what it does is only visible as secondary effects on other drivers and subsystems, without their explicit involvement or knowledge. In that respect, hiding its activity can arguably lead to more non-obvious situations than many other subsystems. > If all subsystems would print messages that are useful > when looking at issues, things would be quite nasty verbose. From a personal standpoint, can we at least eradicate all the "Hi! I'm a driver/subsystem you don't even have the hardware for!" messages first, then maybe come back and reconsider the ones that convey actual information later? Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu