From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id 73C393855018 for ; Tue, 22 Jun 2021 07:29:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 73C393855018 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-338-4YhcV3qaMhSctj3YhZ1CNQ-1; Tue, 22 Jun 2021 03:29:29 -0400 X-MC-Unique: 4YhcV3qaMhSctj3YhZ1CNQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AB944804142; Tue, 22 Jun 2021 07:29:28 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-211.ams2.redhat.com [10.36.112.211]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8C23B1346F; Tue, 22 Jun 2021 07:29:23 +0000 (UTC) From: Florian Weimer To: Kurt Kanzenbach Cc: Adhemerval Zanella , libc-alpha@sourceware.org, Carlos O'Donell , Thomas Gleixner , Sebastian Andrzej Siewior Subject: Re: [PATCH RFC 0/3] nptl: Introduce and use FUTEX_LOCK_PI2 References: <20210621111650.1164689-1-kurt@linutronix.de> <87h7hql5qm.fsf@kurt> Date: Tue, 22 Jun 2021 09:29:21 +0200 In-Reply-To: <87h7hql5qm.fsf@kurt> (Kurt Kanzenbach's message of "Tue, 22 Jun 2021 09:26:41 +0200") Message-ID: <871r8ugxwu.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.4 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, KAM_NUMSUBJECT, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Jun 2021 07:29:32 -0000 * Kurt Kanzenbach: > At this point __ASSUME_FUTEX_LOCK_PI2 is false meaning the kernel does > not have FUTEX_LOCK_PI2 support. But, it calls FUTEX_LOCK_PI2 for > clockid monotonic. This will result in ENOSYS unless it's an old kernel > which is patched. Is that intended? That's not quite how the __ASSUME_* macros work. If not defined, it just means that glibc won't assume that the kernel feature is there. It can still use it (the run-time kernel might have it after all), but glibc has to check for the feature and has to compile in some sort of fallback code. Thanks, Florian