From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755955AbXL2CWs (ORCPT ); Fri, 28 Dec 2007 21:22:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754159AbXL2CWk (ORCPT ); Fri, 28 Dec 2007 21:22:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:57097 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754155AbXL2CWk (ORCPT ); Fri, 28 Dec 2007 21:22:40 -0500 From: Andi Kleen Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) To: Adrian Bunk Subject: Re: [PATCH] x86: unify x86 Makefile(s) Date: Sat, 29 Dec 2007 03:14:23 +0100 User-Agent: KMail/1.9.6 Cc: Sam Ravnborg , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , LKML References: <20071228212341.GA6939@uranus.ravnborg.org> <20071228221324.GA9105@does.not.exist> In-Reply-To: <20071228221324.GA9105@does.not.exist> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200712290314.23567.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 28 December 2007 23:13:24 Adrian Bunk wrote: > On Fri, Dec 28, 2007 at 10:23:41PM +0100, Sam Ravnborg wrote: > >... > > Noteworthy remarks on the unification: > >... > > - -funit-at-a-time should be easy to unify but it looks like we have a bug > > in 32 bit. We only enable -funit-at-a-time for gcc less than 0400 if they > > support it > > No, we _dis_able it on 32bit if a gcc < 4.0 supports it. > > > (and I recall it is a gcc 4.00 feature). [-lt -> -gt] > >... > > unit-at-a-time was introduced in upstream gcc 3.4 and backported to some > popular 3.3 x86_64 branch. > > i386 and x86_64 go in exactly opposite directions regarding when to use > unit-at-a-time, but that was intentional and we should keep it that way. i386 disabled it because there were claims that it increased stack size too much, but I haven't seen any real evidence for that. That is why I never added it to x86-64. On the other hand it tends to shrink text size considerably. I think it should be reevaluated and enabled by default on i386 again. BTW there is a patch pending for gcc 4.3+ that prevents optimizations that increase stack size unduly. Not sure it has been added there yet, but that was the right fix for these problems anyways. -Andi