Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753646Ab2KTRIo (ORCPT ); Tue, 20 Nov 2012 12:08:44 -0500 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:37389 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752894Ab2KTRIn (ORCPT ); Tue, 20 Nov 2012 12:08:43 -0500 Date: Tue, 20 Nov 2012 17:08:17 +0000 From: Will Deacon To: Robert Richter Cc: Maynard Johnson , "jgq516@gmail.com" , "linux@arm.linux.org.uk" , "oprofile-list@lists.sf.net" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH 1/1] ARM: oprofile: add A5/A7/A15 entries in op_perf_name Message-ID: <20121120170817.GG27765@mudshark.cambridge.arm.com> References: <1351853016-4476-1-git-send-email-jgq516@gmail.com> <20121105113102.GF3351@mudshark.cambridge.arm.com> <20121120121747.GJ2504@rric.localhost> <20121120155717.GD26475@mudshark.cambridge.arm.com> <20121120163158.GO2504@rric.localhost> <20121120165517.GC27765@mudshark.cambridge.arm.com> <20121120170601.GR2504@rric.localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121120170601.GR2504@rric.localhost> 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 Content-Length: 1646 Lines: 37 On Tue, Nov 20, 2012 at 05:06:01PM +0000, Robert Richter wrote: > On 20.11.12 16:55:17, Will Deacon wrote: > > On Tue, Nov 20, 2012 at 04:31:58PM +0000, Robert Richter wrote: > > > I am thinking of the following: > > > > > > # cat /root/cpu_type > > > arm/armv7-ca5 > > > # cat /dev/oprofile/cpu_type > > > unknown > > > # mount --bind /root/cpu_type /dev/oprofile/cpu_type > > > # cat /dev/oprofile/cpu_type > > > arm/armv7-ca5 > > > > > > From here legacy oprofile tools work as expected using oprofilefs. (I > > > think. Did not test it.) We need to change the kernel for this a bit > > > to return 'unknown'. The mount could be done by the oprofile tools > > > using existing cpu detection code. This is only one way to setup > > > cpu_type from userland, there could be other ways too. > > > > Ok, this is functionally equivalent to the patch that was submitted at the > > start of this thread: it solves the problem of mapping a single ARM core to > > a oprofile's CPU ID string. Technically, I don't mind doing that in the > > kernel (at least, it means you don't need to do your trick above) > > The advantage of a solution where userland updates cpu_type is that we > never need to update the kernel anymore. This means, cpu detection can > be part of the tools. True, but the kernel-side perf code still needs updating to support the new CPU so I don't think you win much. Will -- 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/