Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752438AbaB0FbO (ORCPT ); Thu, 27 Feb 2014 00:31:14 -0500 Received: from terminus.zytor.com ([198.137.202.10]:49882 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750781AbaB0FbN (ORCPT ); Thu, 27 Feb 2014 00:31:13 -0500 Message-ID: <530ECBB1.40806@zytor.com> Date: Wed, 26 Feb 2014 21:22:57 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Andy Lutomirski CC: Andi Kleen , Stefani Seibold , X86 ML , Greg KH , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Ingo Molnar , Andrea Arcangeli , John Stultz , Pavel Emelyanov , Cyrill Gorcunov , andriy.shevchenko@linux.intel.com, Martin.Runge@rohde-schwarz.com, Andreas.Brief@rohde-schwarz.com Subject: Re: [PATCH 1/2] x86: Mark __vdso entries as asmlinkage References: <20140227033920.GI12219@tassilo.jf.intel.com> <530EC7D1.3000706@zytor.com> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/26/2014 09:19 PM, Andy Lutomirski wrote: >> >> The normal ABI almost certainly makes more sense; as such -mregparm=3 is >> probably not what we want, and I suspect it makes more sense to just >> drop that from the CFLAGS line? > > Hmm. What happens on a native 32-bit build? IIRC the whole kernel is > build with regparm(3). > Well, the vdso is still built separately, so we can use different CFLAGS if we want to. > If we want to save a cycle or two, then regparm(3) is probably faster. > But I think that these functions should either be asmlinkage or (on > 32 bit builds) explicitly regparm(3) to avoid confusion. I suggest using the standard ABI, but I suggest doing it via CFLAGS. It isn't any faster if the C library has to provide a wrapper just to marshal parameters. -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/