From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750937AbVL2UAg (ORCPT ); Thu, 29 Dec 2005 15:00:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750938AbVL2UAg (ORCPT ); Thu, 29 Dec 2005 15:00:36 -0500 Received: from waste.org ([64.81.244.121]:29106 "EHLO waste.org") by vger.kernel.org with ESMTP id S1750936AbVL2UAf (ORCPT ); Thu, 29 Dec 2005 15:00:35 -0500 Date: Thu, 29 Dec 2005 13:56:41 -0600 From: Matt Mackall To: Ulrich Drepper Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, linux-tiny@selenic.com Subject: Re: Fwd: [PATCH] Make sysenter support optional Message-ID: <20051229195641.GB3356@waste.org> References: <20051228212402.GX3356@waste.org> <43B30E19.6080207@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43B30E19.6080207@redhat.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 28, 2005 at 02:13:45PM -0800, Ulrich Drepper wrote: > > This adds configurable sysenter support on x86. This saves about 5k on > > small systems. > > You not only remove the sysenter support but also the vdso. And the > later is a very bad idea. It is already today basically impossible to > have reliable backtraces without the vdso and the unwind info it > contains for signal handlers. And things can only get worse in future. > The magic heuristics in the compiler are not reliable. It's simply the > wrong face, this in a interface between the kernel and the libc, the > compiler should not have such knowledge. > > The vdso should be mandatory for all configurations. It's under CONFIG_EMBEDDED. Think uclibc. Think systems without interactive shells. -- Mathematics is the supreme nostalgia of our time.