Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757400AbYAJCqj (ORCPT ); Wed, 9 Jan 2008 21:46:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754752AbYAJCq3 (ORCPT ); Wed, 9 Jan 2008 21:46:29 -0500 Received: from terminus.zytor.com ([198.137.202.10]:54262 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754676AbYAJCq2 (ORCPT ); Wed, 9 Jan 2008 21:46:28 -0500 Message-ID: <478586E1.8010709@zytor.com> Date: Wed, 09 Jan 2008 18:45:53 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Andi Kleen CC: Jeff Dike , Miklos Szeredi , harvey.harrison@gmail.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net Subject: Re: uml and -regparm=3 References: <20080109213258.GC15612@one.firstfloor.org> <20080110021404.GA11287@c2.user-mode-linux.org> <20080110023701.GB20813@one.firstfloor.org> In-Reply-To: <20080110023701.GB20813@one.firstfloor.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1314 Lines: 28 Andi Kleen wrote: > On Wed, Jan 09, 2008 at 09:14:04PM -0500, Jeff Dike wrote: >> On Wed, Jan 09, 2008 at 10:50:48PM +0100, Miklos Szeredi wrote: >>>> 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. >>> __down_write() in include/asm-x86/rwsem.h seems to assume, that the >>> semaphore pointer is passed in %eax down to rwsem_down_write_failed(), >>> so regparm does make a difference there. >> And rwsem_down_write_failed seems to think it's getting the pointer in >> %eax: > > That's a left over from when it was called by magic inline assembly. > I suspect it would be better to switch it just over to stack args > for consistent and then declare it asmlinkage > That seems to go in the wrong direction to me. It would make more sense to gradually shift to asmlinkage actually being regparm=3. This, of course, would require a different name (such as FASTCALL) until the conversion is complete -- even if done as a single patch series. -hpa -- 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/