From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752103AbcB2IBt (ORCPT ); Mon, 29 Feb 2016 03:01:49 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:36643 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751978AbcB2IBr (ORCPT ); Mon, 29 Feb 2016 03:01:47 -0500 Date: Mon, 29 Feb 2016 09:01:43 +0100 From: Ingo Molnar To: Stephen Rothwell Cc: "H. Peter Anvin" , Dave Hansen , linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu, peterz@infradead.org, linux-next@vger.kernel.org, deller@gmx.de Subject: Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Message-ID: <20160229080143.GB31950@gmail.com> References: <20160226173427.54A6949F@viggo.jf.intel.com> <6C5C3B9B-CAD6-4010-9A3E-AFFF7E13FAE3@zytor.com> <20160227091013.6e0606d1@canb.auug.org.au> <20160227114154.GA16200@gmail.com> <56D1F61C.5050308@sr71.net> <9E8119F8-1F37-4084-AE31-34CA6DE8C15E@zytor.com> <20160228102629.0ef4ef4f@canb.auug.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160228102629.0ef4ef4f@canb.auug.org.au> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Stephen Rothwell wrote: > > u32? > > It would have to be __u32, but we already use int and unsigned int > extensively in the siginfo structure (which are both always assumed to > be 32 bits). So "unsigned int" probably makes most sense. No. This whole mishap is an object lesson in why it's a bad idea to ever use ABI types outside of the __[us][8|16|32|64] space: some of them are 'fine', some of them (like longs) are not. And we have to start somewhere, so we might as well start with new code that adds new ABI details: if a patch only uses __[us][8|16|32|64] types then it's easier to tell whether it's a safe ABI extension. Thanks, Ingo