From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932343AbbDNW24 (ORCPT ); Tue, 14 Apr 2015 18:28:56 -0400 Received: from mout.kundenserver.de ([212.227.126.187]:50230 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754239AbbDNW2t (ORCPT ); Tue, 14 Apr 2015 18:28:49 -0400 From: Arnd Bergmann To: Catalin Marinas Cc: linux-arm-kernel@lists.infradead.org, Andreas Kraschitzer , Benedikt Huber , "Pinski, Andrew" , "linux-kernel@vger.kernel.org" , Andrew Pinski , Kumar Sankaran , "Dr. Philipp Tomsich" , Christoph Muellner Subject: Re: [PATCH v4 00/24] ILP32 for ARM64 Date: Wed, 15 Apr 2015 00:28:09 +0200 Message-ID: <2947000.5TRODaJfhK@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <20150414150034.GF14546@e104818-lin.cambridge.arm.com> References: <2069111.6po5Xr33Dn@wuerfel> <20150414150034.GF14546@e104818-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:g8I7xVNChszgzB1Cx2BPQabFr0XS4AwfN1ZqvrRWdDIUPb2xXMD UW8e3i6rJrltWo9oF7d+RtUw0YyoxxXJn3JO2H3BVUpQKshyqESqYpNv9VK96gUBut3XtMj B7xRpZwHbMk8RDcLfdgmJmiQ3CqBYE03LkOjeiGs/vZPLY/0noO2J+jRadvgS+sk/+seDfB Q5lSkUsRAFBKkyVzleDBQ== X-UI-Out-Filterresults: notjunk:1; Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 14 April 2015 16:00:34 Catalin Marinas wrote: > On Tue, Apr 14, 2015 at 04:07:36PM +0200, Arnd Bergmann wrote: > > For completeness, there is yet another option, which would be to use the > > exact system call table from arm64 and do all the emulation in user space > > rather than the kernel. This would however be the least compatible with > > existing source code, so you probably don't want to do that. > > It would be great if this worked but I think we looked at it before and > it seems nice until you hit the futex stuff and robust lists (I don't > fully remember the details). Some of the structures (siginfo) would no > longer be POSIX compliant and some of them aren't only accessed via libc > to be able to create shadow copies. Well, that may or may not be acceptable. Aarch64-ilp32 mode is a hack to enable a very special class of applications, it's not like anyone would want to run a full system for this and need POSIX compliance. We could definitely be pragmatic and do whatever helps get the job done. That said, it diverges further from what legacy 32-bit applications expect to see, so this approach will likely make an application port harder, not easier. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Wed, 15 Apr 2015 00:28:09 +0200 Subject: [PATCH v4 00/24] ILP32 for ARM64 In-Reply-To: <20150414150034.GF14546@e104818-lin.cambridge.arm.com> References: <2069111.6po5Xr33Dn@wuerfel> <20150414150034.GF14546@e104818-lin.cambridge.arm.com> Message-ID: <2947000.5TRODaJfhK@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 14 April 2015 16:00:34 Catalin Marinas wrote: > On Tue, Apr 14, 2015 at 04:07:36PM +0200, Arnd Bergmann wrote: > > For completeness, there is yet another option, which would be to use the > > exact system call table from arm64 and do all the emulation in user space > > rather than the kernel. This would however be the least compatible with > > existing source code, so you probably don't want to do that. > > It would be great if this worked but I think we looked at it before and > it seems nice until you hit the futex stuff and robust lists (I don't > fully remember the details). Some of the structures (siginfo) would no > longer be POSIX compliant and some of them aren't only accessed via libc > to be able to create shadow copies. Well, that may or may not be acceptable. Aarch64-ilp32 mode is a hack to enable a very special class of applications, it's not like anyone would want to run a full system for this and need POSIX compliance. We could definitely be pragmatic and do whatever helps get the job done. That said, it diverges further from what legacy 32-bit applications expect to see, so this approach will likely make an application port harder, not easier. Arnd