From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753467Ab1ICR2v (ORCPT ); Sat, 3 Sep 2011 13:28:51 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53356 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752895Ab1ICR2u (ORCPT ); Sat, 3 Sep 2011 13:28:50 -0400 Message-ID: <4E62638E.40308@zytor.com> Date: Sat, 03 Sep 2011 10:27:42 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.20) Gecko/20110817 Fedora/3.1.12-1.fc14 Thunderbird/3.1.12 MIME-Version: 1.0 To: Valdis.Kletnieks@vt.edu CC: Arnd Bergmann , "H.J. Lu" , Linus Torvalds , Christoph Hellwig , LKML , Ingo Molnar , Thomas Gleixner , Richard Kuo , Mark Salter , Jonas Bonn , Tobias Klauser Subject: Re: RFD: x32 ABI system call numbers References: <4E582577.2060805@zytor.com> <4E61BB42.4090301@zytor.com> <8179020.mG8hWW8BRr@wuerfel> <14427.1315058668@turing-police.cc.vt.edu> <9b6a2b8e-365f-4155-85ca-5f72b46a7f3e@email.android.com> <19229.1315070217@turing-police.cc.vt.edu> In-Reply-To: <19229.1315070217@turing-police.cc.vt.edu> 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 On 09/03/2011 10:16 AM, Valdis.Kletnieks@vt.edu wrote: >> >> The complexity of changing that would be enormous. > > Oh, I know changing the x86-32 ABI is impossible - I meant changing the > decision to emulate that ABI (as opposed to emulating the x86-64 ABI, or a > variant thereof, or something else). Or are we already commited to that > route, even if we're still trying to figure out what syscalls to include? > About ioctl in particular, the ABI has dependencies into almost every single driver in the Linux kernel. It is hard-coded in the kernel that there are two paths -- native and compat. Since pointers are going to be 4 bytes, it means we have to use the compat path. We may be able to cheat a little bit since we encode the argument sizes in the ioctl numbers; this solves the case of PPGETTIME/PPSETTIME for example (in fact, this ioctl looks currently broken in compat mode!) However, at some point the sheer number of data types that can be consumed by ioctl is a real concern, so changing the ones we really care about -- like timespec/timeval -- while leaving the rest intact so we can use the compat path as a general rule would be highly useful. -hpa