Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261152AbTINNzI (ORCPT ); Sun, 14 Sep 2003 09:55:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261153AbTINNzI (ORCPT ); Sun, 14 Sep 2003 09:55:08 -0400 Received: from mail.jlokier.co.uk ([81.29.64.88]:13459 "EHLO mail.jlokier.co.uk") by vger.kernel.org with ESMTP id S261152AbTINNzD (ORCPT ); Sun, 14 Sep 2003 09:55:03 -0400 Date: Sun, 14 Sep 2003 14:54:31 +0100 From: Jamie Lokier To: Andi Kleen Cc: linux-kernel@vger.kernel.org, jh@suse.cz Subject: Re: stack alignment in the kernel was Re: nasm over gas? Message-ID: <20030914135431.GB16525@mail.jlokier.co.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 852 Lines: 23 Andi Kleen wrote: > The stack adjustments are for getting good performance with floating > point code. Most x86 CPUs require 16 byte alignment for floating point > stores/loads on the stack. It can make a dramatic difference in some > FP intensive programs. You're right. > A compiler option to turn it off would make sense to save .text space > and eliminate these useless instructions. Especially since the kernel > entry points make no attempt to align the stack to 16 byte anyways, > so most likely the stack adjustments do not even work. There is an option: -mpreferred-stack-boundary=2 -- Jamie - 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/