Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 10 Dec 2002 00:44:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 10 Dec 2002 00:44:31 -0500 Received: from deviant.impure.org.uk ([195.82.120.238]:16061 "EHLO deviant.impure.org.uk") by vger.kernel.org with ESMTP id ; Tue, 10 Dec 2002 00:44:30 -0500 Date: Tue, 10 Dec 2002 05:52:15 +0000 From: Dave Jones To: Joseph Cc: linux-kernel@vger.kernel.org Subject: Re: Why does C3 CPU downgrade in kernel 2.4.20? Message-ID: <20021210055215.GA9124@suse.de> Mail-Followup-To: Dave Jones , Joseph , linux-kernel@vger.kernel.org References: <009f01c2a000$f38885d0$3716a8c0@taipei.via.com.tw> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <009f01c2a000$f38885d0$3716a8c0@taipei.via.com.tw> User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 938 Lines: 24 On Tue, Dec 10, 2002 at 12:02:25PM +0800, Joseph wrote: > Hi all, > I rebuilt the 2.4.20 kernel with C3 CPU and found it been downgraded to > i486. > And I check the file, linux/arch/i386/Makefile, in both of 2.4.19 and > 2.4.20 kernels. > In 2.4.19, the CFLAGS adds "-march=i586". > But in 2.4.20, the CFLAGS adds > "-march=i486 -malign-functions=0 -malign-jumps=0 -malign-loops=0". > Why do this? Could anybody explain this to me? I believe someone (Jeff Garzik?) benchmarked gcc code generation, and the C3 executed code scheduled for a 486 faster than it did for -m586 I'm not sure about the alignment flags. I've been meaning to look into that myself... Dave - 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/