From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 2B6F31F461 for ; Thu, 18 Jul 2019 08:19:05 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:references:date:in-reply-to :message-id:mime-version:content-type; q=dns; s=default; b=kYT+C tYL1j3RnMrGPlazq01VCylzMuQCbAU5z8I5dsRc3F9al5dv+um/3riFFkUzxB0yA 37fcY++T0NSB4/vmyD1Iqz9yOxeYpBQl0tCMpm8aurxtJ9kQdS9ckGYZ2i6FTCMC tndfyk41slXIriHRrIjiFy257sUQobwLUAnqQ4= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:references:date:in-reply-to :message-id:mime-version:content-type; s=default; bh=U5cb/WjUHgQ /T5J2nkBauNOAIyM=; b=jlcsIE171NrGt2tunbxkQ7vGKjo0mM/9RpJvNyFdErz xJsWY4aMC40DiaK7HXKasHtTj+4dRX6wYzg7E2i3i00qT/kn7kn5ePm28rE3IGyD AiwbjtHCAWRemm4JpZWXOXYtEUHtF+nQh6CO5A+mL/4giweWF6DUgzlLAHCB8Pd4 = Received: (qmail 100312 invoked by alias); 18 Jul 2019 08:19:02 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 100301 invoked by uid 89); 18 Jul 2019 08:19:02 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: mx1.redhat.com From: Florian Weimer To: Arnd Bergmann Cc: Alistair Francis , GNU C Library , Adhemerval Zanella , Palmer Dabbelt , macro@wdc.com, Zong Li , Alistair Francis Subject: Re: [RFC v3 04/23] sysdeps/clock_gettime: Use clock_gettime64 if avaliable References: <1f589e5a3fcaa4c103bc83169fffcdea9e1a6b2d.1563321715.git.alistair.francis@wdc.com> <87ftn5dxu8.fsf@oldenburg2.str.redhat.com> <87zhldaw4r.fsf@oldenburg2.str.redhat.com> <87y30w7kty.fsf@oldenburg2.str.redhat.com> Date: Thu, 18 Jul 2019 10:18:56 +0200 In-Reply-To: (Arnd Bergmann's message of "Thu, 18 Jul 2019 09:38:49 +0200") Message-ID: <87y30v3gcv.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain * Arnd Bergmann: > I have two ideas for how that could be done: > > - When building for a minimum kernel version of 5.1, don't > fall back to __vdso_clock_gettime() or syscall(__NR_clock_gettime) > but use the slow path for __clock_gettime64() if the vdso doesn't > work. Assuming that clock_gettime64 support is available, yes. > - if __vdso_clock_gettime64() is unavailable and __vdso_clock_gettime() > returns negative seconds, fall back to syscall(__NR_clock_gettime). I don't want to do anything like this. I expect that some of us will eventually use time namespaces to keep programs running (with incorrect time). If we make glibc itself time-sensitive, then things will get horribly complex. > Would either of those meet your requirements? I don't have requirements. I just want something that has limited impact on 64-bit architectures. I don't think probing at startup is too bad, actually. Thanks, Florian