From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760625AbaEMNj1 (ORCPT ); Tue, 13 May 2014 09:39:27 -0400 Received: from mout.kundenserver.de ([212.227.17.24]:59174 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753943AbaEMNjZ (ORCPT ); Tue, 13 May 2014 09:39:25 -0400 From: Arnd Bergmann To: Geert Uytterhoeven Cc: Thomas Gleixner , Ley Foon Tan , James Hogan , Linux-Arch , LKML , Chung-Lin Tang Subject: Re: [PATCH 01/25] asm-generic: Change time_t and clock_t to 64 bit Date: Tue, 13 May 2014 15:38:51 +0200 Message-ID: <6047893.vbvIgNOHCV@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.11.0-18-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: References: <1399971456-3941-1-git-send-email-lftan@altera.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V02:K0:BV/NILKSXT/TaGH7jZl3V4TRy6F3UJtzZ+uDaDkA698 5DzEzrAzCUmTyTMo5zyzmRRiMehL+VJrWnQVulDFC6ZjIMo9h2 75NDoXVLnuJ3w3fJMMJoOM45ao6koJXh8PTvduGFyU+oPRzuca X6mjYiFruh5jOQMJxEYpjFoONL1bpXJXDZNneUk9oawT9f1MBL ZDcHu0YpM38HQL/o9ZmBoPqh8Urt10g7ezXXqF4z9t+BF3ZN0+ h3yWX4Cx7Euw0c4VwIKlE1OKT8ywcVcoZv13Vdgx4F6AK1aBe+ awYlqHaWOIeBDRr36fk2Wy7Ue8VJjCUGmTbIl2RAGfAsz2jv/Q 484sDFaqHeIDKOS9KI8Y= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 13 May 2014 15:11:33 Geert Uytterhoeven wrote: > On Tue, May 13, 2014 at 2:07 PM, Thomas Gleixner wrote: > > On Tue, 13 May 2014, Arnd Bergmann wrote: > >> On Tuesday 13 May 2014 18:17:40 Ley Foon Tan wrote: > >> > When we export this posix_types.h file for user software, they need to > >> > define this config, eg: CONFIG_32BIT_TIME to use 32 bit time. Is this > >> > what we want to do? > >> > >> No, this doesn't really work: You can't use CONFIG_* symbols in > >> user-visible header files. > > > > Then make the config symbol generate the header from a template. > > Indeed. I think it's worthwhile to add CONFIG_* expansion for such "hard" > CONFIG symbols to make headers_install, cfr. the existing unifdef support. > > We do such a hard work to improve asm-generic, so new architectures can > just use that, only to see early adaptors now having to migrate away from it > (e.g. OpenRISC suddenly gaining uapi/asm/posix_types.h). This was always the idea: New architectures should use the default ABI as it is defined at the time when they get added. When we later change the ABI, everything that is already there is no longer using the default, so they now have to change. > Or is there another solution? We could in theory have a versioned ABI, and define for instance that openrisc uses the 3.1 version while nios2 uses the 3.16 version. Doing that would introduce other problems I guess, but it would avoid the use of changing lots of architectures when the default ABI changes. Arnd