From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C41EC00A89 for ; Fri, 30 Oct 2020 14:18:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C5352076E for ; Fri, 30 Oct 2020 14:18:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726654AbgJ3OSK (ORCPT ); Fri, 30 Oct 2020 10:18:10 -0400 Received: from l2mail1.panix.com ([166.84.1.75]:52470 "EHLO l2mail1.panix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725834AbgJ3OSJ (ORCPT ); Fri, 30 Oct 2020 10:18:09 -0400 X-Greylist: delayed 924 seconds by postgrey-1.27 at vger.kernel.org; Fri, 30 Oct 2020 10:18:09 EDT Received: from mailbackend.panix.com (mailbackend.panix.com [166.84.1.89]) by l2mail1.panix.com (Postfix) with ESMTPS id 4CN3sx748pzDTD for ; Fri, 30 Oct 2020 10:02:45 -0400 (EDT) Received: from mail-ej1-f46.google.com (mail-ej1-f46.google.com [209.85.218.46]) by mailbackend.panix.com (Postfix) with ESMTPSA id 4CN3sx0g0gz1f9f for ; Fri, 30 Oct 2020 10:02:45 -0400 (EDT) Received: by mail-ej1-f46.google.com with SMTP id 7so8817516ejm.0 for ; Fri, 30 Oct 2020 07:02:45 -0700 (PDT) X-Gm-Message-State: AOAM531TOLUaX9vwHWw53k7zZnNiUXnu/ZtcarnWgLJZ4jLJnA4PcWgw md/KDQoP9P5pQgx8H23NmdqOpaWGh0m7NxNAqYU= X-Google-Smtp-Source: ABdhPJw8J+4cOp1WFt2Gq3nyQkJW+64glQjsML0SG/NZY2/Qa+/sII201MUJIn8DpG9MrwQhAiHM0Dkna9wLvnU2q8M= X-Received: by 2002:a17:906:2895:: with SMTP id o21mr2759315ejd.332.1604066564183; Fri, 30 Oct 2020 07:02:44 -0700 (PDT) MIME-Version: 1.0 References: <20201030110229.43f0773b@jawa> <20201030135816.GA1790@yuki.lan> In-Reply-To: <20201030135816.GA1790@yuki.lan> From: Zack Weinberg Date: Fri, 30 Oct 2020 10:02:29 -0400 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [Y2038][time namespaces] Question regarding CLOCK_REALTIME support plans in Linux time namespaces To: Cyril Hrubis Cc: Lukasz Majewski , Thomas Gleixner , Andrei Vagin , GNU C Library , Linux Kernel Mailing List , Dmitry Safonov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 30, 2020 at 9:57 AM Cyril Hrubis wrote: > > According to patch description [1] and time_namespaces documentation > > [2] the CLOCK_REALTIME is not supported (for now?) to avoid complexity > > and overhead in the kernel. ... > > To be more specific - [if this were supported] it would be possible to modify time after time_t > > 32 bit overflow (i.e. Y2038 bug) on the process running Y2038 > > regression tests on the host system (64 bit one). By using Linux time > > namespaces the system time will not be affected in any way. > > And what's exactly wrong with moving the system time forward for a > duration of the test? Interference with other processes on the same computer? Some of us *do* like to run the glibc test suite on computers not entirely devoted to glibc CI. zw