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 41E283857820 for ; Thu, 20 May 2021 06:50:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 41E283857820 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-176-ixS7Wid5P2-JZtG-eZNLmg-1; Thu, 20 May 2021 02:50:24 -0400 X-MC-Unique: ixS7Wid5P2-JZtG-eZNLmg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6D281107ACCA; Thu, 20 May 2021 06:50:23 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-137.ams2.redhat.com [10.36.112.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9C06F1037F2A; Thu, 20 May 2021 06:50:22 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella via Libc-alpha Subject: Re: [PATCH v2 06/25] linux: Add fallback for 64-bit time_t SO_TIMESTAMP{NS} References: <20210518205613.1487824-1-adhemerval.zanella@linaro.org> <20210518205613.1487824-7-adhemerval.zanella@linaro.org> Date: Thu, 20 May 2021 08:50:20 +0200 In-Reply-To: <20210518205613.1487824-7-adhemerval.zanella@linaro.org> (Adhemerval Zanella via Libc-alpha's message of "Tue, 18 May 2021 17:55:54 -0300") Message-ID: <87v97dsxub.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 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, 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: Thu, 20 May 2021 06:50:27 -0000 * Adhemerval Zanella via Libc-alpha: > Calls with __TIMESIZE=32 will see the converted 64-bit time control > messages as spurious control message of unknown type. Calls with > __TIMESIZE=64 running on pre-time64 kernels will see the original > message as a spurious control ones of unknown typ while running on > kernel with native 64-bit time support will only see the time64 version > of the control message. Does the mirror what the kernel does? I have some concerns about backwards compatibility here, but if the kernel does it as well, that is likely a non-issue. I think this kind of emulation goes against our general guidance of not emulating system calls in userspace. It would probably be necessary if we switch an existing 32-bit target to 64-bit time_t by default, though. Thanks, Florian