Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754233AbZKLUEi (ORCPT ); Thu, 12 Nov 2009 15:04:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754112AbZKLUEg (ORCPT ); Thu, 12 Nov 2009 15:04:36 -0500 Received: from gate.crashing.org ([63.228.1.57]:51797 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753994AbZKLUEf (ORCPT ); Thu, 12 Nov 2009 15:04:35 -0500 Subject: Re: [PATCH 5/6] hw-breakpoints: Arbitrate access to pmu following registers constraints From: Benjamin Herrenschmidt To: Frederic Weisbecker Cc: Paul Mackerras , Ingo Molnar , LKML , Prasad , Alan Stern , Peter Zijlstra , Arnaldo Carvalho de Melo , Steven Rostedt , Jan Kiszka , Jiri Slaby , Li Zefan , Avi Kivity , Mike Galbraith , Masami Hiramatsu , Paul Mundt In-Reply-To: <20091112155413.GE5237@nowhere> References: <1257275474-5285-1-git-send-email-fweisbec@gmail.com> <1257275474-5285-6-git-send-email-fweisbec@gmail.com> <19186.45014.502448.698606@cargo.ozlabs.ibm.com> <1257713781.13611.284.camel@pasglop> <20091112155413.GE5237@nowhere> Content-Type: text/plain; charset="UTF-8" Date: Fri, 13 Nov 2009 07:00:38 +1100 Message-ID: <1258056038.2140.354.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1074 Lines: 31 On Thu, 2009-11-12 at 16:54 +0100, Frederic Weisbecker wrote: > > - On one embedded core at least we have a case where the core has 4 > > threads, but the data (4) and instruction (2) breakpoint registers are > > shared. The 'enable' bits are split so a given data breakpoint can be > > enabled only on some HW threads but that's about it. > > > > I'm not sure if there's a realistic way to handle the later constraint > > though other than just not allowing use of the HW breakpoint function on > > those cores at all. > > > > Ben. > > > Yeah this latter one is tricky. Not sure how to handle it either. > How are these hw-threads considered by the kernel core? As different > cpu? Yes. So it basically looks like you have 4 data and 2 HW instruction breakpoint registers shared by 4 CPUs in a group :-) Cheers, Ben. -- 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/