From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761381Ab2D0UbL (ORCPT ); Fri, 27 Apr 2012 16:31:11 -0400 Received: from mga14.intel.com ([143.182.124.37]:32723 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760239Ab2D0UbJ (ORCPT ); Fri, 27 Apr 2012 16:31:09 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="93971036" Message-ID: <4F9B020B.9050205@linux.intel.com> Date: Fri, 27 Apr 2012 13:31:07 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1 MIME-Version: 1.0 To: Sam Ravnborg CC: Steven Rostedt , LKML , linux-kbuild , Michal Marek , Andrew Morton , Andi Kleen , Ingo Molnar , Frederic Weisbecker Subject: Re: RFC: How to handle function tracing, frame pointers and -mfentry? References: <1335552399.28106.228.camel@gandalf.stny.rr.com> <20120427202701.GA5949@merkur.ravnborg.org> In-Reply-To: <20120427202701.GA5949@merkur.ravnborg.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/27/2012 01:27 PM, Sam Ravnborg wrote: >> >> My question is, how do I remove the dependency in kconfig based on the >> compiler? > > Allow the user to select one of: > 1) function tracer > 2) frame pointer > 3) none of the above > > This should be trivial to do in Kconfig language. > > If "function tracer" is selected then use -mfentry if supported, > with a fallback to frame pointers. > > This looks simple IMO and should be easy to implement too. > Except it is the wrong thing. This is not the only user of frame pointer. What I think you mean is remove the dependency in Kconfig, but force the frame pointer enabled if -mfentry is not supported. -hpa