Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964794AbVL1ME7 (ORCPT ); Wed, 28 Dec 2005 07:04:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964796AbVL1ME7 (ORCPT ); Wed, 28 Dec 2005 07:04:59 -0500 Received: from mx1.redhat.com ([66.187.233.31]:31930 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S964794AbVL1ME6 (ORCPT ); Wed, 28 Dec 2005 07:04:58 -0500 Date: Wed, 28 Dec 2005 07:04:35 -0500 From: Jakub Jelinek To: Ingo Molnar Cc: lkml , Linus Torvalds , Andrew Morton , Arjan van de Ven , Matt Mackall Subject: Re: [patch 02/2] allow gcc4 to optimize unit-at-a-time Message-ID: <20051228120435.GS22293@devserv.devel.redhat.com> Reply-To: Jakub Jelinek References: <20051228114701.GC3003@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051228114701.GC3003@elte.hu> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1790 Lines: 42 On Wed, Dec 28, 2005 at 12:47:01PM +0100, Ingo Molnar wrote: > allow gcc4 compilers to optimize unit-at-a-time - which results in gcc > having a wider scope when optimizing. This also results in smaller code > when optimizing for size. (gcc4 does not have the stack footprint > problem of gcc3 compilers.) > > Signed-off-by: Ingo Molnar > Signed-off-by: Arjan van de Ven > ---- > > arch/i386/Makefile | 6 +++--- > 1 files changed, 3 insertions(+), 3 deletions(-) > > Index: linux/arch/i386/Makefile > =================================================================== > --- linux.orig/arch/i386/Makefile > +++ linux/arch/i386/Makefile > @@ -42,9 +42,9 @@ include $(srctree)/arch/i386/Makefile.cp > GCC_VERSION := $(call cc-version) > cflags-$(CONFIG_REGPARM) += $(shell if [ $(GCC_VERSION) -ge 0300 ] ; then echo "-mregparm=3"; fi ;) > > -# Disable unit-at-a-time mode, it makes gcc use a lot more stack > -# due to the lack of sharing of stacklots. > -CFLAGS += $(call cc-option,-fno-unit-at-a-time) > +# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use > +# a lot more stack due to the lack of sharing of stacklots: > +CFLAGS += $(shell if [ $(GCC_VERSION) -lt 0400 ] ; then echo "-fno-unit-at-a-time"; fi ;) -fno-unit-at-a-time option has been introduced in GCC 3.4 (and 3.3-hammer branch). So unless the minimum supported GCC version to compile kernel is 3.4+, you need to replace echo "-fno-unit-at-a-time" with $(call cc-option,-fno-unit-at-a-time) . Jakub - 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/