From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752071AbcELGpM (ORCPT ); Thu, 12 May 2016 02:45:12 -0400 Received: from merlin.infradead.org ([205.233.59.134]:60534 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750725AbcELGpK (ORCPT ); Thu, 12 May 2016 02:45:10 -0400 Date: Thu, 12 May 2016 08:42:01 +0200 From: Peter Zijlstra To: Vineet Gupta Cc: acme@redhat.com, Vince Weaver , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-snps-arc@lists.infradead.org, mingo@kernel.org Subject: Re: [RFC 2/2] perf/core: change errno for sampling event not supported in hardware Message-ID: <20160512064201.GL3192@twins.programming.kicks-ass.net> References: <1462786660-2900-1-git-send-email-vgupta@synopsys.com> <1462786660-2900-3-git-send-email-vgupta@synopsys.com> <5730C79F.3060307@synopsys.com> <20160511193627.GH3190@twins.programming.kicks-ass.net> <5734229B.90706@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5734229B.90706@synopsys.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 12, 2016 at 11:58:43AM +0530, Vineet Gupta wrote: > On Thursday 12 May 2016 01:06 AM, Peter Zijlstra wrote: > > On Mon, May 09, 2016 at 10:53:43PM +0530, Vineet Gupta wrote: > > > >> > Right thats what I feared. But hold on, I don't think we need to change the ABI to > >> > achieve what we want. Gosh why did I even take that path. > >> > > >> > Currently the errno switch case in perf_evsel__open_strerror() in doesn't handle > >> > ENOTSUPP. So how about we add that - augmented with the same sample_period !0 > >> > check to barf for lack of sampling support. > >> > > >> > Do you see anything wrong with that ? > > > > Should work I think. > > Tried that and doesn't even compile. Reconfirms what Vince said, ENOTSUPP is not > exposed to userspace (being in include/linux and not include/uapi/linux) Durr, so what does userspace see?