From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755415AbaHANVX (ORCPT ); Fri, 1 Aug 2014 09:21:23 -0400 Received: from one.firstfloor.org ([193.170.194.197]:54385 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754684AbaHANVW (ORCPT ); Fri, 1 Aug 2014 09:21:22 -0400 Date: Fri, 1 Aug 2014 15:21:20 +0200 From: Andi Kleen To: Peter Zijlstra Cc: kan.liang@intel.com, andi@firstfloor.org, alexander.shishkin@linux.intel.com, linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner Subject: Re: [PATCH 2/3] x86 perf: Protect LBR msrs accessing against potential #GP Message-ID: <20140801132120.GO18735@two.firstfloor.org> References: <1406799663-18192-1-git-send-email-kan.liang@intel.com> <1406799663-18192-2-git-send-email-kan.liang@intel.com> <20140801073825.GG19379@twins.programming.kicks-ass.net> <20140801074430.GB3588@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140801074430.GB3588@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > NAK! > > > > I already said this isn't going to ever happen. > > > > Both PT and LBR are arbitrated through the kernel, therefore we can (and > > must) deny PT when there's existing LBR usage and vice versa. > > > > We will not hijack resources like this full stop end of story. > > > > Fuck hardware/BIOS, they should _NOT_ be touching this. > > > > The 3 people in the world with access to an x86 hardware debugger had > > better be competent and know WTF they're doing and the BIOS can just > > piss off right now, they should not be touching this _EVER_. So you realize that hardware level debugging becomes impossible if everyone starts using perf? I dont know how anyone can construct essentially sabotaging powerful debugging techniques ever as a good thing. In the end it'll just lead to more buggy software (and likely hardware) for everyone. > > I yelled at BIOS engineers over their PMU usage and $vendor added a BIOS > knob to disable that, I'll yell at BIOS engineers again, just give me > their number. > > Really, say NO already. Ok, so no technical reason, merely a "me vs you" power play. Thank you for not stating that earlier and wasting everyone's time. -Andi -- ak@linux.intel.com -- Speaking for myself only.