From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937255AbYEUVpr (ORCPT ); Wed, 21 May 2008 17:45:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759361AbYEUVpc (ORCPT ); Wed, 21 May 2008 17:45:32 -0400 Received: from pasmtpb.tele.dk ([80.160.77.98]:60573 "EHLO pasmtpB.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756116AbYEUVpb (ORCPT ); Wed, 21 May 2008 17:45:31 -0400 Date: Wed, 21 May 2008 23:46:08 +0200 From: Sam Ravnborg To: Mathieu Desnoyers Cc: "H. Peter Anvin" , linux-kernel@vger.kernel.org, Jeremy Fitzhardinge , Ingo Molnar Subject: Re: [PATCH] Fix Immediate Values x86_64 support old gcc Message-ID: <20080521214608.GA15136@uranus.ravnborg.org> References: <482AB6C5.4060604@goop.org> <20080516124811.GC4226@Krystal> <482DFD65.10300@zytor.com> <20080521133122.GA18084@Krystal> <48344239.9070003@zytor.com> <20080521160217.GA26974@Krystal> <20080521170150.GA29428@Krystal> <20080521203743.GA12982@uranus.ravnborg.org> <20080521212809.GE6158@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080521212809.GE6158@Krystal> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 21, 2008 at 05:28:09PM -0400, Mathieu Desnoyers wrote: > * Sam Ravnborg (sam@ravnborg.org) wrote: > > Hi Mathieu > > > Does this fix make more sense ? > > > > > > GCC < 4, on x86_64, does not accept symbol+offset operands for "i" constraints > > > asm statements. Fallback on generic immediate values if this compiler is > > > detected. > > > > > > Signed-off-by: Mathieu Desnoyers > > > --- > > > arch/x86/Makefile | 3 +++ > > > arch/x86/kernel/Makefile | 4 +++- > > > include/asm-x86/immediate.h | 5 +++++ > > > include/linux/immediate.h | 4 +++- > > > kernel/Makefile | 4 +++- > > > 5 files changed, 17 insertions(+), 3 deletions(-) > > > > > > Index: linux-2.6-sched-devel/arch/x86/Makefile > > > =================================================================== > > > --- linux-2.6-sched-devel.orig/arch/x86/Makefile 2008-05-21 09:04:52.000000000 -0400 > > > +++ linux-2.6-sched-devel/arch/x86/Makefile 2008-05-21 09:22:05.000000000 -0400 > > > @@ -78,6 +78,9 @@ > > > "$(CC)" -fstack-protector-all ) > > > > > > KBUILD_CFLAGS += $(stackp-y) > > > + > > > + export GCC_BROKEN_IMMEDIATE > > > + GCC_BROKEN_IMMEDIATE := $(shell if [ $(call cc-version) -lt 0400 ] ; then echo "y"; fi) > > > > So here we introduce a global environment variable that tells > > us that gcc has "BROKEN_IMMEDIATE". > > I have absolutely no clue what "BROKEN_IMMEDIATE" is so I guess others > > are in the same boat. Comment please! > > > > Yes, I guess this worth being commented, you are right. I'll write > something along the lines written in the patch header. > > > Consider something like this (note: no negative logic involved): > > export USE_IMMEDIATE := $(call cc-ifversion, -ge, 0400, $(CONFIG_IMMEDIATE)) > > > > Hrm, if I do that, I would have to add USE_IMMEDIATE to each > architecture's makefiles for which immediate values are supported, e.g.: > > export USE_IMMEDIATE := $(CONFIG_IMMEDIATE) > > The "BROKEN_IMMEDIATE" (negative) approach only needs to be defined on > x86_64 where gcc 3.x does not support symbol+offset correctly. Same with USE_IMMEDIATE - as USE_IMMEDIATE is only used in a x86 Makefile. Or did I miss sothing? Sam