Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756763AbYAIVae (ORCPT ); Wed, 9 Jan 2008 16:30:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754216AbYAIVa0 (ORCPT ); Wed, 9 Jan 2008 16:30:26 -0500 Received: from one.firstfloor.org ([213.235.205.2]:49101 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753616AbYAIVa0 (ORCPT ); Wed, 9 Jan 2008 16:30:26 -0500 Date: Wed, 9 Jan 2008 22:32:58 +0100 From: Andi Kleen To: Miklos Szeredi Cc: andi@firstfloor.org, harvey.harrison@gmail.com, jdike@addtoit.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net Subject: Re: uml and -regparm=3 Message-ID: <20080109213258.GC15612@one.firstfloor.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1380 Lines: 39 On Wed, Jan 09, 2008 at 10:20:49PM +0100, Miklos Szeredi wrote: > > Miklos Szeredi writes: > > > > > FASTCALL is defined empty in -mm, but UML is not compiled with > > > -mregparm=3 and so this breaks things (I noticed problems with > > > rwsem_down_write_failed). > > > > > > Tried recompiling UML with -mregparm=3, but that resulted in a strange > > > failure immediately after startup: > > > > > > |%G�%@: Invalid argument > > > > > > What's up? > > > > UML links with glibc and that does not use -mregparm. > > > > You can only use -mregparm in user space if you recompile > > all libraries too. > > Ah, right. I didn't think of that. > > Does that mean that FASTCALL removals will have to be undone? Or is > there an alternative? FASTCALL is useless and should not make a difference. It enables regparm on specific functions, but that should not make a difference if it works or not. For working -mregparm you will need asmlinkage on all functions that interface with assembler code to disable regparms for them. The only exception is system calls which have the arguments on the stack too. -Andi -- 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/