From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932084AbWBWRrc (ORCPT ); Thu, 23 Feb 2006 12:47:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932091AbWBWRrb (ORCPT ); Thu, 23 Feb 2006 12:47:31 -0500 Received: from terminus.zytor.com ([192.83.249.54]:8632 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S932084AbWBWRra (ORCPT ); Thu, 23 Feb 2006 12:47:30 -0500 Message-ID: <43FDF52C.6020407@zytor.com> Date: Thu, 23 Feb 2006 09:47:24 -0800 From: "H. Peter Anvin" User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Benjamin LaHaise CC: "David S. Miller" , klibc@zytor.com, linux-kernel@vger.kernel.org Subject: Re: sys_mmap2 on different architectures References: <43FCDB8A.5060100@zytor.com> <20060223001411.GA20487@kvack.org> <20060222.164347.12864037.davem@davemloft.net> <20060223173907.GF27682@kvack.org> In-Reply-To: <20060223173907.GF27682@kvack.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Benjamin LaHaise wrote: > On Wed, Feb 22, 2006 at 04:43:47PM -0800, David S. Miller wrote: > >>Aha, that part I didn't catch. Thanks for the clarification >>Ben. >> >>I wonder why we did things that way with a fixed shift... > > > Without that trick, we'd have needed an extra parameter for the syscall > on x86, which is already at the maximum number of registers with 6 > arguments. This was easier than changing the syscall ABI. =-) > Well, there is always the trick of making it a pointer. It was needed for pselect() anyway. A real sys_mmap64 would definitely have been cleaner, and will be needed to deal with the 16 TB barrier anyway :) I personally think the S390 people had the right idea... once you run out of registers, just make it a defined part of the ABI that we pass in a single pointer to all the arguments. -hpa