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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B0198C4363A for ; Fri, 30 Oct 2020 15:10:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2BDDC2071A for ; Fri, 30 Oct 2020 15:10:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="LQFVw4VU"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="b4KDRU00" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726815AbgJ3PK3 (ORCPT ); Fri, 30 Oct 2020 11:10:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725975AbgJ3PK2 (ORCPT ); Fri, 30 Oct 2020 11:10:28 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95C0AC0613CF for ; Fri, 30 Oct 2020 08:10:28 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1604070626; 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: in-reply-to:in-reply-to:references:references; bh=9wGjxMvPHeaomJM6gSl6Q4fS9j3pKCTwNKb3PNq3yZo=; b=LQFVw4VUE7tdqEBCFqu31Pz7As2+jhO0blrnSzV5nUp0hVM16cQGyQmsZSzkSCmIyZ3qFj Po0pj2R3tixui1jUox7SIBiwSdzC4mxePcZwOHKRIDIb0bl4/ZrzR2HMxYZD0P31ZRiGFX dR3+uInKvkT8vGEwzMrf0Judr7/X5iYcW512fa8F0e0ZArODZKUEaVsuWuhwIsMdWtgPFb lRFIu1a5KB+zEKNQO7IZUU5IgvtXQTUT4O/6lrHR7nC5cE5JuRPYcxxKMwXJl4B/dU4293 d0rZ8ik/Hi0MJEQxrKaww9raLmyJ4VjK4Y2bxUl3Ye9O9qeKW2iHpGoiuQ68Xw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604070626; 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: in-reply-to:in-reply-to:references:references; bh=9wGjxMvPHeaomJM6gSl6Q4fS9j3pKCTwNKb3PNq3yZo=; b=b4KDRU00/mUt7SdS5Y+Dcay+FeC0fPmUHW8pIiJbNaLNqIXlR0lFb5AQsA2TzNmt6u+QdB 6g/5FLd2CTMbHsCw== To: Zack Weinberg , Cyril Hrubis Cc: Lukasz Majewski , Andrei Vagin , GNU C Library , Linux Kernel Mailing List , Dmitry Safonov Subject: Re: [Y2038][time namespaces] Question regarding CLOCK_REALTIME support plans in Linux time namespaces In-Reply-To: References: <20201030110229.43f0773b@jawa> <20201030135816.GA1790@yuki.lan> Date: Fri, 30 Oct 2020 16:10:26 +0100 Message-ID: <87sg9vn40t.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 30 2020 at 10:02, Zack Weinberg wrote: > 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. That's what virtual machines are for.