Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932562AbaJXNCo (ORCPT ); Fri, 24 Oct 2014 09:02:44 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:45350 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756434AbaJXNCm (ORCPT ); Fri, 24 Oct 2014 09:02:42 -0400 Date: Fri, 24 Oct 2014 15:02:28 +0200 From: Peter Zijlstra To: Alexander Shishkin Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Robert Richter , Frederic Weisbecker , Mike Galbraith , Paul Mackerras , Stephane Eranian , Andi Kleen , kan.liang@intel.com, adrian.hunter@intel.com, acme@infradead.org Subject: Re: [PATCH v5 12/20] x86: perf: intel_pt: Intel PT PMU driver Message-ID: <20141024130228.GM3219@twins.programming.kicks-ass.net> References: <1413207948-28202-1-git-send-email-alexander.shishkin@linux.intel.com> <1413207948-28202-13-git-send-email-alexander.shishkin@linux.intel.com> <20141022144543.GV12706@worktop.programming.kicks-ass.net> <87tx2t27yb.fsf@ashishki-desk.ger.corp.intel.com> <20141024115131.GY21513@worktop.programming.kicks-ass.net> <87wq7pd5sw.fsf@ashishki-desk.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87wq7pd5sw.fsf@ashishki-desk.ger.corp.intel.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 Fri, Oct 24, 2014 at 03:13:19PM +0300, Alexander Shishkin wrote: > Peter Zijlstra writes: > > > On Fri, Oct 24, 2014 at 11:22:20AM +0300, Alexander Shishkin wrote: > >> > The fact that the hardware cannot even tell you the supported mask is > >> > further fail. > > > >> The problem with this is that some bits go in groups, there'd be 2..3..4 > >> bit fields encoding desired packet frequency, for example. > > > > OK, so put the magic number in the big model array. > > I'm not sure I follow. These bits are reserved for the future, they can > potentially be whatever combinations of whatever. If we want to probe > around for valid combinations is to check everything in the range of > 0..2^43 (or something like that, the region reserved for packet enables) > and store all the valid ones, which sounds crazy. I was assuming that the accepted bits are model specific, and we have this big model switch statement in perf_event_intel.c:intel_pmu_init(), so why not have something like x86_pmu.pt_magic_bitmask = 0xf00d in there? No need to probe in that case. That is the same thing we do for all unenumerated model specific things. -- 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/