From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/7004 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.kernel,gmane.comp.lib.glibc.alpha,gmane.linux.lib.musl.general,gmane.linux.ports.arm.kernel Subject: Re: [PATCHv3 00/24] ILP32 support in ARM64 Date: Thu, 12 Feb 2015 11:13:54 -0500 Message-ID: <20150212161354.GT23507@brightrain.aerifal.cx> References: <20150210181302.GA23886@brightrain.aerifal.cx> <20150211190252.GB23507@brightrain.aerifal.cx> <20150211192558.GE23507@brightrain.aerifal.cx> <20150211194741.GI23507@brightrain.aerifal.cx> <54DBB87C.5060901@amacapital.net> <20150212155023.GA25491@e104818-lin.cambridge.arm.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1423757680 14230 80.91.229.3 (12 Feb 2015 16:14:40 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 12 Feb 2015 16:14:40 +0000 (UTC) Cc: Andy Lutomirski , "H.J. Lu" , GNU C Library , Andrew Pinski , musl@lists.openwall.com, LKML , Andrew Pinski , "linux-arm-kernel@lists.infradead.org" To: Catalin Marinas Original-X-From: linux-kernel-owner@vger.kernel.org Thu Feb 12 17:14:32 2015 Return-path: Envelope-to: glk-linux-kernel-3@plane.gmane.org Original-Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YLwPN-0004av-GQ for glk-linux-kernel-3@plane.gmane.org; Thu, 12 Feb 2015 17:14:29 +0100 Original-Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756079AbbBLQOZ (ORCPT ); Thu, 12 Feb 2015 11:14:25 -0500 Original-Received: from 216-12-86-13.cv.mvl.ntelos.net ([216.12.86.13]:37011 "EHLO brightrain.aerifal.cx" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755716AbbBLQOX (ORCPT ); Thu, 12 Feb 2015 11:14:23 -0500 Original-Received: from dalias by brightrain.aerifal.cx with local (Exim 3.15 #2) id 1YLwOo-00040h-00; Thu, 12 Feb 2015 16:13:54 +0000 Content-Disposition: inline In-Reply-To: <20150212155023.GA25491@e104818-lin.cambridge.arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Xref: news.gmane.org gmane.linux.kernel:1887380 gmane.comp.lib.glibc.alpha:49215 gmane.linux.lib.musl.general:7004 gmane.linux.ports.arm.kernel:393097 Archived-At: On Thu, Feb 12, 2015 at 03:50:24PM +0000, Catalin Marinas wrote: > On Wed, Feb 11, 2015 at 12:15:56PM -0800, Andy Lutomirski wrote: > > On 02/11/2015 11:57 AM, H.J. Lu wrote: > > >>>>trivially satisfied if you consider x32 and x86_64 separate > > >>>>compilation environments, but it's not related to the core issue: that > > >>>>the definition of timespec violates core (not obscure) requirements of > > >>>>both POSIX and C11. At the time you were probably unaware of the C11 > > >>>>requirement. Note that it's a LOT harder to effect change in the C > > >>>>standard, so even if the Austin Group would be amenable to changing > > >>>>the requirement for timespec to allow something like nseconds_t, > > >>>>getting WG14 to make this change to work around a Linux/glibc mistake > > >>>>does not sound practical. > > >>> > > >>>That is very unfortunate. I consider it is too late for x32 to change. > > >> > > >>Why? It's hardly an incompatible ABI change, as long as the > > >>kernel/libc fills the upper bits (for old programs that read them > > >>based on the old headers) when structs are read from the kernel to the > > >>application, and ignores the upper bits (potentially set or left > > >>uninitialized by the application) when strings are passed from > > >>userspace to the kernel. Newly built apps using the struct definition > > >>with 32-bit tv_nsec would need new libc to ensure that the high bits > > >>aren't interpreted, but this could be handled by symbol versioning. > > >> > > > > > >We have considered this option. But since kernel wouldn't change > > >tv_nsec/tv_usec handling just for x32, it wasn't selected. > > > > Did anyone *ask* the kernel people (e.g. hpa)? > > It seems so: > > https://lkml.org/lkml/2011/8/31/244 > > Couple of more replies from hpa: > > https://lkml.org/lkml/2011/8/31/261 > https://lkml.org/lkml/2012/2/8/408 > > It looks like hpa was going to talk the POSIX committee but I don't know > what the conclusion was and didn't follow the thread (at the time I > wasn't interested in ARM ILP32). At this point POSIX committee is not sufficient. ISO C specifies timespec now, and as Jens Gustedt mentioned (I don't think his reply made it to the whole CC list; see the musl list archive here: http://www.openwall.com/lists/musl/2015/02/11/21 ), it seems unlikely that one could pose a convincing argument for this requirement to be changed in the C language. Rich