From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759443Ab2INLnx (ORCPT ); Fri, 14 Sep 2012 07:43:53 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:60526 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758835Ab2INLnq (ORCPT ); Fri, 14 Sep 2012 07:43:46 -0400 Message-ID: <5053186E.6000302@gmail.com> Date: Fri, 14 Sep 2012 05:43:42 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:15.0) Gecko/20120907 Thunderbird/15.0.1 MIME-Version: 1.0 To: Ingo Molnar CC: acme@ghostprotocols.net, linux-kernel@vger.kernel.org, peterz@infradead.org, Robert Richter Subject: Re: [PATCH 3/3 v2] perf tool: give user better message if precise is not supported References: <1347569955-54626-1-git-send-email-dsahern@gmail.com> <1347569955-54626-4-git-send-email-dsahern@gmail.com> <20120914054344.GB9043@gmail.com> <50531151.9020202@gmail.com> <20120914113617.GA13299@gmail.com> In-Reply-To: <20120914113617.GA13299@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/14/12 5:36 AM, Ingo Molnar wrote: > Well, then that is useful information we *lost*, and that > situation needs to be improved on the ABI side: an expanded > error code present in the event structure, copied back to > user-space on errors, or so. > > (Alternatively, a special event channel just to pass back > expanded error conditions.) > > Computers are supposed to make life easier for humans, by > answering such "what did go wrong?" questions. Our losing of > precise error conditions is a usability bug really - and in the > perf project we are in a unique position to be able to improve > both the kernel side code and make immediate use of it on the > tooling side as well. Understood and there have been suggestions on how to definitely state what the kernel side did not like. I like Peter's last suggestion -- something along the lines of clearing attr on a failure except the offending setting. David