From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262827AbVEONAP (ORCPT ); Sun, 15 May 2005 09:00:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262829AbVEONAP (ORCPT ); Sun, 15 May 2005 09:00:15 -0400 Received: from colin.muc.de ([193.149.48.1]:33297 "EHLO mail.muc.de") by vger.kernel.org with ESMTP id S262827AbVEONAJ (ORCPT ); Sun, 15 May 2005 09:00:09 -0400 Date: 15 May 2005 15:00:08 +0200 Date: Sun, 15 May 2005 15:00:08 +0200 From: Andi Kleen To: Adrian Bunk Cc: linux-kernel@vger.kernel.org Subject: Re: [-mm patch] i386: enable REGPARM by default Message-ID: <20050515130008.GA72644@muc.de> References: <20050515115712.GQ16549@stusta.de> <20050515123729.GT16549@stusta.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050515123729.GT16549@stusta.de> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 15, 2005 at 02:37:31PM +0200, Adrian Bunk wrote: > On Sun, May 15, 2005 at 02:22:34PM +0200, Andi Kleen wrote: > > Adrian Bunk writes: > > > > > This patch should _not_ go into Linus' tree. > > > > > > At some time in the future, we want to unconditionally enable REGPARM on > > > i386. > > > > > > Let's give it a bit broader testing coverage among -mm users. > > > > iirc problem is that gcc 2.95 and possibly 3.0.x have some known > > miscompilations with regparams. That is why it was only used > > with fastcall for a long time. One 3.1.x+ it should be safe. > > But you cannot express dependencies on the compiler version > > in Kconfig right now. > > > > Of course getting rid of gcc 2.95 and 3.0.x support would be a good idea, > > that would allow many other nice things. > > If you'd read either arch/i386/Makefile or the help text for > CONFIG_REGPARM, you'd have noticed that we do never use regparm with > gcc < 3.0 . Yes, this means you cannot have binary compatible kernels compiled with different compilers. Which might be a bad thing. For that reason alone I would keep the config. -Andi