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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 65A79FA3728 for ; Wed, 16 Oct 2019 10:39:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 458072168B for ; Wed, 16 Oct 2019 10:39:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404265AbfJPKjl (ORCPT ); Wed, 16 Oct 2019 06:39:41 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:49674 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726259AbfJPKjk (ORCPT ); Wed, 16 Oct 2019 06:39:40 -0400 Received: from [5.158.153.52] (helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iKgi0-0002yS-J6; Wed, 16 Oct 2019 12:39:12 +0200 Date: Wed, 16 Oct 2019 12:39:11 +0200 (CEST) From: Thomas Gleixner To: Vincenzo Frascino cc: Dmitry Safonov , linux-kernel@vger.kernel.org, Dmitry Safonov <0x7f454c46@gmail.com>, Andrei Vagin , Adrian Reber , Andy Lutomirski , Arnd Bergmann , Christian Brauner , Cyrill Gorcunov , "Eric W. Biederman" , "H. Peter Anvin" , Ingo Molnar , Jann Horn , Jeff Dike , Oleg Nesterov , Pavel Emelyanov , Shuah Khan , containers@lists.linux-foundation.org, criu@openvz.org, linux-api@vger.kernel.org, x86@kernel.org, Andrei Vagin Subject: Re: [PATCHv7 01/33] ns: Introduce Time Namespace In-Reply-To: <80af93da-d497-81de-2a2a-179bb3bc852d@arm.com> Message-ID: References: <20191011012341.846266-1-dima@arista.com> <20191011012341.846266-2-dima@arista.com> <80af93da-d497-81de-2a2a-179bb3bc852d@arm.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 16 Oct 2019, Vincenzo Frascino wrote: < Trim 250+ lines ( 3+ pages) of pointlessly wasted electrons > > > --- a/init/Kconfig > > +++ b/init/Kconfig > > @@ -1096,6 +1096,13 @@ config UTS_NS > > In this namespace tasks see different info provided with the > > uname() system call > > > > +config TIME_NS > > + bool "TIME namespace" > > + default y > > Having CONFIG_TIME_NS "default y" makes so that the option is selected even on > the architectures that have no support for time namespaces. > The direct consequence is that the fallbacks defined in this patch are never > selected and this ends up in kernel compilation errors due to missing symbols. > > The error below shows what happens on arm64 (similar behavior on other > architectures): > > aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork': > kernel/time/namespace.c:321: undefined reference to `vdso_join_timens' > > My proposal is to keep TIME_NS "default n" (just remove "default y"), let the > architectures that enable time namespaces select it and make CONFIG_TIME_NS > select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO. Nah. config TIME_NS bool "TIME namespace" depends on GENERIC_VDSO_TIME_NS default y and in lib/vdso/Kconfig config GENERIC_VDSO_TIME_NS bool and let architectures which have support for the VDSO bits select it. < Trim another gazillion of useless lines > See: https://people.kernel.org/tglx/notes-about-netiquette Thanks, tglx