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=-3.9 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 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 CDC48C4363A for ; Fri, 30 Oct 2020 13:08:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59557206FA for ; Fri, 30 Oct 2020 13:08:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="3ow5LXhQ"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="hDdBeq3H" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726591AbgJ3NIu (ORCPT ); Fri, 30 Oct 2020 09:08:50 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:42376 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725999AbgJ3NIt (ORCPT ); Fri, 30 Oct 2020 09:08:49 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1604063328; 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=XCaYMdTrl3RnP9DiH91VC3uvp6vlZ27bXHklu69/ezs=; b=3ow5LXhQS3wYOfqUW6gcHW9UDA0t4QduDNbdJXHWUuCAalcVAQJ7/Am1xpy9SBMTBYGAKU Ithm5j3jPDk5BKmVKm/88+Z+X3Iasi1ms5VQY57UFRNMxxl6g0swnXHWK8ztKs0N/GSdnT /UxLVweNxE1enula+FbXnzHUc1brhvZpSoc/dSiz83oxwP4yu8/6Eenpw9jJGp817EDk0k PP/swJmL5EYOG9f/fRj2bvJJvJ9Dr/NTAY69BsJFu0nRmWYOTC1NCekACn06yoOQVxfTwH XruxyZxExREl00yVFVxsIF+zahjdQ8Ztla3bXTQVvc0sOs62q2cYojzarAoZ6g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604063328; 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=XCaYMdTrl3RnP9DiH91VC3uvp6vlZ27bXHklu69/ezs=; b=hDdBeq3Hs6KfDQHzUMktWKE/YmSvKFFMVM8anc5fZJzJCW2ZKAj+noHlhL538R/RjgaGTe gdaDRqGepZubRnBQ== To: Lukasz Majewski , Andrei Vagin , Dmitry Safonov Cc: GNU C Library , Arnd Bergmann , linux-kernel@vger.kernel.org Subject: Re: [Y2038][time namespaces] Question regarding CLOCK_REALTIME support plans in Linux time namespaces In-Reply-To: <20201030110229.43f0773b@jawa> References: <20201030110229.43f0773b@jawa> Date: Fri, 30 Oct 2020 14:08:48 +0100 Message-ID: <871rhfoo7z.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 Lukasz, On Fri, Oct 30 2020 at 11:02, Lukasz Majewski wrote: > I do have a question regarding the Linux time namespaces in respect of > adding support for virtualizing the CLOCK_REALTIME. > > 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. > > Is there any plan to add support for it in a near future? Not really. Just having an offset on clock realtime would be incorrect in a number of ways. Doing it correct is a massive trainwreck. For a debug aid, which is what you are looking for, the correctness would not really matter, but providing that is a really slippery slope. If at all we could hide it under a debug option which depends on CONFIG_BROKEN and emitting a big fat warning in dmesg with a clear statement that it _is_ broken, stays so forever and any attempt to "fix" it results in a permanent ban from all kernel lists. Preferrably we don't go there. Thanks, tglx