From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dedi548.your-server.de (dedi548.your-server.de [85.10.215.148]) by sourceware.org (Postfix) with ESMTPS id CAB223857C5A for ; Mon, 13 Jul 2020 06:19:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org CAB223857C5A Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=embedded-brains.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=sebastian.huber@embedded-brains.de Received: from sslproxy03.your-server.de ([88.198.220.132]) by dedi548.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1jurns-0002yW-MN; Mon, 13 Jul 2020 08:19:04 +0200 Received: from [82.100.198.138] (helo=mail.embedded-brains.de) by sslproxy03.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92) (envelope-from ) id 1jurns-00030J-Hd; Mon, 13 Jul 2020 08:19:04 +0200 Received: from localhost (localhost.localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id 61DCE2A1610; Mon, 13 Jul 2020 08:19:32 +0200 (CEST) Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id ITpodvbRaWzX; Mon, 13 Jul 2020 08:19:32 +0200 (CEST) Received: from localhost (localhost.localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id 1CDDA2A1681; Mon, 13 Jul 2020 08:19:32 +0200 (CEST) X-Virus-Scanned: amavisd-new at zimbra.eb.localhost Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id dUT_K4S1LLFS; Mon, 13 Jul 2020 08:19:32 +0200 (CEST) Received: from huber-nb-linux.suse (unknown [192.168.96.142]) by mail.embedded-brains.de (Postfix) with ESMTPSA id 05EC22A1610; Mon, 13 Jul 2020 08:19:32 +0200 (CEST) To: Newlib From: Sebastian Huber Subject: fenv support vs. SMP systems Message-ID: Date: Mon, 13 Jul 2020 08:19:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: quoted-printable X-Authenticated-Sender: smtp-embedded@poldinet.de X-Virus-Scanned: Clear (ClamAV 0.102.3/25871/Sun Jul 12 16:05:43 2020) X-Spam-Status: No, score=0.0 required=5.0 tests=BAYES_00, FOREIGN_BODY, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, TXREP, T_FILL_THIS_FORM_SHORT autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: newlib@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Newlib mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Jul 2020 06:19:07 -0000 Hello, the new fenv support alters usually some floating-point status and=20 control register. This register is usually specific to the processor=20 executing the code. In an SMP system, the current approach can lead to=20 an inconsistent system if the register is not included in the thread=20 context (for example in RTEMS these registers are considered to be=20 system wide and are only initialized during the system startup). What do=20 I mean with inconsistent system? For example, you set the rounding mode=20 on processor A to from X (=3D default) to Y, then the you migrate to=20 processor B and suddenly use the default rounding mode X. Another=20 example is to do a division by zero on processor A and then migrate to=20 processor B and check the exception flags. --=20 Sebastian Huber, embedded brains GmbH Address : Dornierstr. 4, D-82178 Puchheim, Germany Phone : +49 89 189 47 41-16 Fax : +49 89 189 47 41-09 E-Mail : sebastian.huber@embedded-brains.de PGP : Public key available on request. Diese Nachricht ist keine gesch=C3=A4ftliche Mitteilung im Sinne des EHUG= .