From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757979AbdDRUTx (ORCPT ); Tue, 18 Apr 2017 16:19:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44328 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754108AbdDRUTu (ORCPT ); Tue, 18 Apr 2017 16:19:50 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 0F9963D95F Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jpoimboe@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 0F9963D95F Date: Tue, 18 Apr 2017 15:19:42 -0500 From: Josh Poimboeuf To: Andi Kleen Cc: kbuild test robot , kbuild-all@01.org, linux-kernel@vger.kernel.org, Ingo Molnar , Steven Rostedt Subject: Re: arch/x86//kernel/ftrace.c:35:3: error: #error The following combination is not supported: ((compiler missing -mfentry) || (CONFIG_X86_32 and !CONFIG_DYNAMIC_FTRACE)) && CONFIG_FUNCTION_GRAPH_TRACER && CONFIG_CC_OPTIMIZE_FOR_SIZE Message-ID: <20170418201942.ohybixihlk36it4t@treble> References: <201704160947.iSmcgQi7%fengguang.wu@intel.com> <20170417133313.ibbt5nmp76xzabf4@treble> <87lgqxtuo6.fsf@firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87lgqxtuo6.fsf@firstfloor.org> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 18 Apr 2017 20:19:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 18, 2017 at 11:52:41AM -0700, Andi Kleen wrote: > Josh Poimboeuf writes: > > > > The error is working as designed. gcc < 4.6.0 doesn't have -mfentry, so > > it fails the above check on x86. Can you add a skip rule? It should > > skip building the following case: > > > > x86 && ((gcc < 4.6.0) || (CONFIG_X86_32 and !CONFIG_DYNAMIC_FTRACE)) > > && CONFIG_FUNCTION_GRAPH_TRACER && CONFIG_CC_OPTIMIZE_FOR_SIZE > > This will also break everyone's randconfig builds. The better way > would be to check this in the Makefile and disable one of the options I don't know how to disable a config option from the Makefile like that. Any ideas? BTW, I think it will only break randconfigs for old versions of gcc, before 4.6.0. The error message isn't quite right. I just noticed the FUNCTION_GRAPH_TRACER config has: depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE which means that X86_32 and CC_OPTIMIZE_FOR_SIZE can never be set with FUNCTION_GRAPH_TRACER. So the error message could be simplified to: #error The following combination is not supported: (compiler missing -mfentry) && CONFIG_FUNCTION_GRAPH_TRACER && CONFIG_CC_OPTIMIZE_FOR_SIZE -- Josh