Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753614AbbBKT6B (ORCPT ); Wed, 11 Feb 2015 14:58:01 -0500 Received: from mail-ob0-f172.google.com ([209.85.214.172]:55539 "EHLO mail-ob0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752282AbbBKT6A (ORCPT ); Wed, 11 Feb 2015 14:58:00 -0500 MIME-Version: 1.0 In-Reply-To: <20150211194741.GI23507@brightrain.aerifal.cx> References: <20141002155217.GH32147@e104818-lin.cambridge.arm.com> <20150210181302.GA23886@brightrain.aerifal.cx> <20150211190252.GB23507@brightrain.aerifal.cx> <20150211192558.GE23507@brightrain.aerifal.cx> <20150211194741.GI23507@brightrain.aerifal.cx> Date: Wed, 11 Feb 2015 11:57:59 -0800 Message-ID: Subject: Re: [PATCHv3 00/24] ILP32 support in ARM64 From: "H.J. Lu" To: Rich Felker Cc: Catalin Marinas , Andrew Pinski , "linux-arm-kernel@lists.infradead.org" , LKML , Andrew Pinski , musl@lists.openwall.com, GNU C Library Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1625 Lines: 34 >> > 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. -- H.J. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/