From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752564AbdLHSXh (ORCPT ); Fri, 8 Dec 2017 13:23:37 -0500 Received: from imap1.codethink.co.uk ([176.9.8.82]:36240 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751937AbdLHSXe (ORCPT ); Fri, 8 Dec 2017 13:23:34 -0500 Message-ID: <1512757408.18523.256.camel@codethink.co.uk> Subject: Re: [Y2038] [PATCH 5/9] y2038: introduce CONFIG_64BIT_TIME From: Ben Hutchings To: Deepa Dinamani Cc: y2038 Mailman List , Thomas Gleixner , John Stultz , Linux Kernel Mailing List , Arnd Bergmann Date: Fri, 08 Dec 2017 18:23:28 +0000 In-Reply-To: References: <20171110224259.15930-1-deepa.kernel@gmail.com> <20171110224259.15930-6-deepa.kernel@gmail.com> <1512752007.18523.254.camel@codethink.co.uk> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2017-12-08 at 09:01 -0800, Deepa Dinamani wrote: > On Fri, Dec 8, 2017 at 8:53 AM, Ben Hutchings > > wrote: > > On Fri, 2017-11-10 at 14:42 -0800, Deepa Dinamani wrote: > > > From: Arnd Bergmann > > > > > > There are a total of 53 system calls (aside from ioctl) that pass a time_t > > > or derived data structure as an argument, and in order to extend time_t > > > to 64-bit, we have to replace them with new system calls and keep providing > > > backwards compatibility. > > > > > > To avoid adding completely new and untested code for this purpose, we > > > introduce a new CONFIG_64BIT_TIME symbol. Every architecture that supports > > > new 64 bit time_t syscalls enables this config via ARCH_HAS_64BIT_TIME. > > > > > > After this is done for all architectures, the CONFIG_64BIT_TIME symbol > > > can be made a user-selected option, to enable users to build a kernel > > > that only provides y2038-safe system calls by making 32 time_t syscalls > > > conditionally included based on the above config. > > > > I don't understand why we would want to change the semantics of > > CONFIG_64BIT_TIME symbol from "enable 64-bit time support" to "disable > > 32-bit time support". > > > > Why not add two config symbols: > > > > config 32BIT_TIME > >         def_bool COMPAT || !64BIT > > > > config 64BIT_TIME > >         def_bool ARCH_HAS_64BIT_TIME > > > > and then make 32BIT_TIME user-configurable later? > > This was already discussed on the review and we have an updated version: > > https://lkml.org/lkml/2017/11/27/938 Sorry, I'll move on to reviewing that. Ben. -- Ben Hutchings Software Developer, Codethink Ltd.