From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752686AbdBFNjT (ORCPT ); Mon, 6 Feb 2017 08:39:19 -0500 Received: from mail.kernel.org ([198.145.29.136]:47854 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752002AbdBFNjO (ORCPT ); Mon, 6 Feb 2017 08:39:14 -0500 Date: Mon, 6 Feb 2017 10:38:59 -0300 From: Arnaldo Carvalho de Melo To: David Carrillo-Cisneros Cc: Mark Rutland , linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Jiri Olsa , Alexander Shishkin , Wang Nan , He Kuang , Michal Marek , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Stephane Eranian , Paul Turner Subject: Re: [PATCH 3/4] tools lib feature: Do not redefine compiler configuration Message-ID: <20170206133859.GB11283@kernel.org> References: <20170202063804.94027-1-davidcc@google.com> <20170202063804.94027-4-davidcc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170202063804.94027-4-davidcc@google.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Wed, Feb 01, 2017 at 10:38:03PM -0800, David Carrillo-Cisneros escreveu: > Feature detection redefines CC, CCX and PKG_CONFIG, making the > output of feature detection inconsistent with the actual features > available during compilation when the above variables are used. > > Fix it by using conditional assignment. This one is tricky, the real meaning of that line got lost somewhere, its original intent, in commit 8b6eb56a9570 ("tools/perf/build: Add 'autodep' functionality, generate feature test dependencies automatically") was to just add that "-MD" to whatever definition CC had, be it the default one or a value set by the user in the make command line. At some point someone added that CROSS_COMPILE there, which it should have gotten from the default CC definition It was here: a8a5cd8b472c ("perf: tools: Fix cross building") perf: tools: Fix cross building Currently the feature-checks Makefile does not inherit $(CC), and calls cc rather than $(CROSS_COMPILE)gcc. Thus the feature checks invoke the native toolchain rather than the cross toolchain, and can identify features as available when they are not. This can break the build ---------------------------------- Mark, do you recall why can't we make tools/perf/Makefile.perf pass the definitions of CC, AR and PKG_CONFIG to tools/perf/config/Makefile (now tools/build/feature/Makefile) so that the original intent (adding -MD to whatever was in CC) can be kept? Jiri? - Arnaldo > Signed-off-by: David Carrillo-Cisneros > --- > tools/build/feature/Makefile | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile > index 3dd2c600d250..d39e76f3a063 100644 > --- a/tools/build/feature/Makefile > +++ b/tools/build/feature/Makefile > @@ -52,9 +52,9 @@ FILES= \ > > FILES := $(addprefix $(OUTPUT),$(FILES)) > > -CC := $(CROSS_COMPILE)gcc -MD > -CXX := $(CROSS_COMPILE)g++ -MD > -PKG_CONFIG := $(CROSS_COMPILE)pkg-config > +CC ?= $(CROSS_COMPILE)gcc -MD > +CXX ?= $(CROSS_COMPILE)g++ -MD > +PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config > LLVM_CONFIG ?= llvm-config > > all: $(FILES) > -- > 2.11.0.483.g087da7b7c-goog