Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964809AbVL1NGn (ORCPT ); Wed, 28 Dec 2005 08:06:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964808AbVL1NGn (ORCPT ); Wed, 28 Dec 2005 08:06:43 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:2000 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S964807AbVL1NGm (ORCPT ); Wed, 28 Dec 2005 08:06:42 -0500 Date: Wed, 28 Dec 2005 14:06:16 +0100 From: Ingo Molnar To: Jakub Jelinek 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: <20051228130616.GA10355@elte.hu> References: <20051228114701.GC3003@elte.hu> <20051228120435.GS22293@devserv.devel.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051228120435.GS22293@devserv.devel.redhat.com> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -1.9 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.9 required=5.9 tests=ALL_TRUSTED,AWL autolearn=no SpamAssassin version=3.0.3 -2.8 ALL_TRUSTED Did not pass through any untrusted hosts 1.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1952 Lines: 53 * Jakub Jelinek wrote: > > +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) > . indeed - updated patch below. Ingo Subject: allow gcc4 to optimize unit-at-a-time 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 $(call cc-option,-fno-unit-at-a-time); fi ;) CFLAGS += $(cflags-y) - 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/