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 4CFD3FA3728 for ; Wed, 16 Oct 2019 10:42:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D63420872 for ; Wed, 16 Oct 2019 10:42:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392504AbfJPKmr (ORCPT ); Wed, 16 Oct 2019 06:42:47 -0400 Received: from foss.arm.com ([217.140.110.172]:35746 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389345AbfJPKmr (ORCPT ); Wed, 16 Oct 2019 06:42:47 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 930B328; Wed, 16 Oct 2019 03:42:46 -0700 (PDT) Received: from [10.37.9.204] (unknown [10.37.9.204]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B02813F6C4; Wed, 16 Oct 2019 03:42:39 -0700 (PDT) Subject: Re: [PATCHv7 01/33] ns: Introduce Time Namespace To: Thomas Gleixner 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 References: <20191011012341.846266-1-dima@arista.com> <20191011012341.846266-2-dima@arista.com> <80af93da-d497-81de-2a2a-179bb3bc852d@arm.com> From: Vincenzo Frascino Message-ID: <5f4c2f29-ca68-b19c-017f-d23730f6e871@arm.com> Date: Wed, 16 Oct 2019 11:44:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/16/19 11:39 AM, Thomas Gleixner wrote: > 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. > Agreed, this is even better. > < Trim another gazillion of useless lines > > > See: https://people.kernel.org/tglx/notes-about-netiquette > > Thanks, > > tglx > -- Regards, Vincenzo