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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 4C8D2C4321D for ; Wed, 15 Aug 2018 15:28:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0901021479 for ; Wed, 15 Aug 2018 15:28:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0901021479 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729819AbeHOSU7 (ORCPT ); Wed, 15 Aug 2018 14:20:59 -0400 Received: from foss.arm.com ([217.140.101.70]:56202 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729300AbeHOSU6 (ORCPT ); Wed, 15 Aug 2018 14:20:58 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8125780D; Wed, 15 Aug 2018 08:28:22 -0700 (PDT) Received: from dupont (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7504C3F5BC; Wed, 15 Aug 2018 08:28:21 -0700 (PDT) Date: Wed, 15 Aug 2018 10:28:20 -0500 From: Kim Phillips To: Will Deacon Cc: Mathieu Poirier , Peter Zijlstra , Arnaldo Carvalho de Melo , Ingo Molnar , Thomas Gleixner , Alexander Shishkin , , , Mark Rutland , Jiri Olsa , Namhyung Kim , Adrian Hunter , , Greg KH , "H. Peter Anvin" , , , Linux Kernel Mailing List , linux-arm-kernel Subject: Re: [PATCH v3 0/7] perf: Add ioctl for PMU driver configuration Message-Id: <20180815102820.3520d0c3875d2fd82300cdef@arm.com> In-Reply-To: <20180815093912.GE2427@arm.com> References: <1531950487-24554-1-git-send-email-mathieu.poirier@linaro.org> <20180813124642.3d49c082a95fc294d926016e@arm.com> <20180814120910.ed225bbc462c58b09e5d68de@arm.com> <20180815093912.GE2427@arm.com> Organization: Arm X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 15 Aug 2018 10:39:13 +0100 Will Deacon wrote: > On Tue, Aug 14, 2018 at 01:42:27PM -0600, Mathieu Poirier wrote: > > On Tue, 14 Aug 2018 at 11:09, Kim Phillips wrote: > > > The other thing that's going on here is that I'm becoming numb to the > > > loathsome "failed to mmap with 12 (Cannot allocate memory)" being > > > returned no matter what the error is/was. E.g., an error that would > > > indicate a sense of non-implementation would be much better > > > appreciated than presumably what the above is doing, i.e., returning > > > -ENOMEM. That, backed up with specific details in the form of human > > > readable text in dmesg would be *most* welcome. > > > > As part of the refactoring of the code to support CPU-wide scenarios I > > intend to emit better diagnostic messages from the driver. Modifying > > rb_alloc_aux() to propagate the error message generated by the > > architecture specific PMUs doesn't look hard either and I _may_ get to > > it as part of this work. > > For the record, I will continue to oppose PMU drivers that dump diagnostics > about user-controlled input into dmesg, but the coresight drivers are yours > so it's up to you and I won't get in the way! That sounds technically self-contradicting to me. Why shouldn't coresight share the same policies as those used for PMU drivers? Or why not allow the individual vendor PMU driver authors control the level of user-friendliness of their own drivers? That being said, Matheiu, would you accept patches that make coresight more verbose in dmesg? Kim