From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS22989 209.51.188.0/24 X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id D837A1F8C6 for ; Mon, 5 Jul 2021 14:32:37 +0000 (UTC) Received: from localhost ([::1]:59124 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m0PeG-0003SF-LK for normalperson@yhbt.net; Mon, 05 Jul 2021 10:32:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41924) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m0PeC-0003Pi-Bu for bug-gnulib@gnu.org; Mon, 05 Jul 2021 10:32:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58937) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m0Pe9-0006Z6-7F for bug-gnulib@gnu.org; Mon, 05 Jul 2021 10:32:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625495546; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Zx3hxEiqiQgA8z4CGZ5c/0jzH7K2T3ndVZe+AR66qSM=; b=UPu9aceJMuHCZMsDF1vIC+1njZqJA6ZnKkv4Cto7ssrL+5G5CkPW0bzuam41fHNjMpRMft 6wMH6vJEQu3xx4Cmxo9N9fAl7XfeDU6Gmy/qYjYQxyuv6UbDQJRGiUm1Pev+WEzIM4uoBi /jradKD3aUbUKshuxs3wxYK62xRjrwc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-333-jXqu3TgTN4eVL8gxZR1FvQ-1; Mon, 05 Jul 2021 10:32:25 -0400 X-MC-Unique: jXqu3TgTN4eVL8gxZR1FvQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CF7891842156; Mon, 5 Jul 2021 14:32:23 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-115-5.ams2.redhat.com [10.36.115.5]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B99B01002D71; Mon, 5 Jul 2021 14:32:22 +0000 (UTC) From: Florian Weimer To: Bruno Haible Subject: Re: [PATCH] year2038: support glibc 2.34 _TIME_BITS=64 References: <20210702023332.2482490-1-eggert@cs.ucla.edu> <878s2ozq70.fsf@oldenburg.str.redhat.com> <4302797.ikRTjI96fm@omega> Date: Mon, 05 Jul 2021 16:32:20 +0200 In-Reply-To: <4302797.ikRTjI96fm@omega> (Bruno Haible's message of "Sat, 03 Jul 2021 00:29:52 +0200") Message-ID: <87y2akltl7.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=fweimer@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=fweimer@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.442, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: bug-gnulib@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Gnulib discussion list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Eggert , bug-gnulib@gnu.org Errors-To: bug-gnulib-bounces+normalperson=yhbt.net@gnu.org Sender: "bug-gnulib" * Bruno Haible: > Hi Florian, > >> > In glibc 2.34 on Linux kernels where time_t is traditionally 32-bit, >> > defining _FILE_OFFSET_BITS=3D64 and _TIME_BITS=3D64 makes time_t 64-bi= t. >> > Apps must define both macros. Gnulib applications that use either >> > the largefile or the year2038 modules will want this behavior; >> > largefile because it deals with the off_t and ino_t components of >> > struct stat already, and so should also deal with time_t. >>=20 >> Won't this be a very disruptive change to distributions, whose system >> libraries have not switched to 64-bit time_t on 32-bit? >>=20 >> gnulib should not try to force a different distribution default. I'm >> worried that this will lead to distributions abandoning 32-bit i386 >> support altogether because the support cost is too high=E2=80=94and you = can't >> even run legacy binaries anymore. > > I don't understand your points regarding "very disruptive change", > "distribution default", and "can't even run legacy binaries". Probably > you have something in mind that differs from my understanding. > > In my understanding, a change like this one propagates to the tarballs > that make use of Gnulib. For example, GNU tar will, starting with the > next version, contain logic that has the effect of adding > #define _TIME_BITS 64 > to the config.h of that package. Thus, GNU tar and GNU mt will, on > glibc =E2=89=A5 2.34 systems, be internally using a different time_t type= than > programs that don't use Gnulib (e.g. util-linux) and programs that use > older versions of Gnulib (e.g. GNU clisp). I assume GNU clisp (at least in a full build) need to link to some system libraries which are not dual ABI (and probably never will be). If gnulib forces the use of time64 mode, then it creates a push towards time64 mode in those libraries, too. At that point, these libraries will no longer be usable for running older binaries (in at least some cases; in others, the time_t symbols are not actually used). > From the perspective of the distributions, this is a no-op, IMO. It is not, gnulib is pushing things in one particular direction, a direction that not everyone working on the GNU toolchain agrees with. > The only problem that I see is with *libraries* that have an API that > references the time_t type. It is well-known that when a library > - references off_t or 'struct stat' in its API, and > - was built with AC_SYS_LARGEFILE in effect, > the packages that use this library also have to be built with > AC_SYS_LARGEFILE. This has caused problems in the past, when > _FILE_OFFSET_BITS=3D64 was introduced (ca. 2000-2005). There are some major differences to _FILE_OFFSET_BITS=3D64: There weren't 20+ years of backwards compatibility in 2005, with a large set of legacy applications. Today, i386 without the ability run legacy programs is fairly useless and perhaps not worth maintaining. 64-bit file offsets enabled real use cases. People usually couldn't address those in another way, given that LP64 CPUs and userspace wasn't yet mainstream. > I don't see big problems with distribution vendors, since 56% > of the distributions have already abandoned i386 ports by now [1], > and more will follow suit. The rest of the distros can easily > add -D_TIME_BITS=3D64 to their common compilation flags. I think those 56% count installation images, not installable i386 library packages on x86-64 systems. Thanks, Florian