From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754642AbaCNNyo (ORCPT ); Fri, 14 Mar 2014 09:54:44 -0400 Received: from mga02.intel.com ([134.134.136.20]:18666 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754024AbaCNNym (ORCPT ); Fri, 14 Mar 2014 09:54:42 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,655,1389772800"; d="scan'208";a="499876462" Date: Fri, 14 Mar 2014 06:54:39 -0700 From: Andi Kleen To: Peter Zijlstra Cc: Andi Kleen , mingo@kernel.org, linux-kernel@vger.kernel.org, eranian@google.com, acme@redhat.com, namhyung@kernel.org, jolsa@redhat.com Subject: Re: [PATCH 1/2] perf, x86: Disallow setting undefined bits for PEBS events Message-ID: <20140314135439.GD3793@tassilo.jf.intel.com> References: <1394745733-27855-1-git-send-email-andi@firstfloor.org> <20140314081338.GL27965@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140314081338.GL27965@twins.programming.kicks-ass.net> 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, Mar 14, 2014 at 09:13:38AM +0100, Peter Zijlstra wrote: > On Thu, Mar 13, 2014 at 02:22:12PM -0700, Andi Kleen wrote: > > From: Andi Kleen > > > > The SDM forbids setting various event qualifiers with PEBS > > events. The magic cycles:pp event uses it, but it has caused > > problems in the past. We continue allowing it for cycles:pp, > > but forbid it for all other events to follow the SDM. > > Last time this came up I asked for what kind of problems it caused. The original PEBS lockup on Sandy Bridge was caused by these bits. The person who architected the hardware strongly advised to not use them with PEBS events. Besides we do what the SDM tells us to do. Do you disagree with that? -Andi -- ak@linux.intel.com -- Speaking for myself only