Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759542AbaKARcG (ORCPT ); Sat, 1 Nov 2014 13:32:06 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:61949 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759147AbaKARcE (ORCPT ); Sat, 1 Nov 2014 13:32:04 -0400 Date: Fri, 31 Oct 2014 12:28:24 +0000 From: Matt Fleming To: Ingo Molnar Cc: Peter Zijlstra , Vince Weaver , Arnaldo Carvalho de Melo , Jiri Olsa , Andy Lutomirski , Stephane Eranian , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [RFD] perf syscall error handling Message-ID: <20141031122824.GZ12020@console-pimps.org> References: <20141030222814.GF15602@worktop.programming.kicks-ass.net> <20141031072109.GD12706@worktop.programming.kicks-ass.net> <20141031092713.GA23124@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141031092713.GA23124@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 31 Oct, at 10:27:13AM, Ingo Molnar wrote: > > - user-space gets back the regular errno (-EOPNOTSUPP or -ENOSYS > or -EINVAL, etc.) and a string. Strings are really the most > helpful information, because tools can just print that. They > can also match on specific strings and programmatically react > to them if they want to: we can promise to not arbitrarily > change error strings once they are introduced. (but even if > they change, user-space can still print them out.) I guess we'd run into a problem if userspace doesn't want to just print the kernel string but instead wants to parse it in some fashion. That may or may not be a problem in practice, Vince can probably comment on that. I'm just thinking along the lines of making the perf syscall interface as useful as possible for tools other than tools/perf. -- Matt Fleming, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/