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 [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id A4EE038708E6 for ; Thu, 4 Feb 2021 10:38:45 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org A4EE038708E6 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-140-LR9msywRNYCK3PstiAQC2Q-1; Thu, 04 Feb 2021 05:38:39 -0500 X-MC-Unique: LR9msywRNYCK3PstiAQC2Q-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3F18A1934136; Thu, 4 Feb 2021 10:38:38 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-116.ams2.redhat.com [10.36.112.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F3F681F464; Thu, 4 Feb 2021 10:38:36 +0000 (UTC) From: Florian Weimer To: "H.J. Lu via Libc-alpha" Cc: Joseph Myers , "H.J. Lu" Subject: Re: [PATCH v2] x86: Require full ISA support for x86-64 level marker [BZ #27318] References: <20210202215112.1002416-1-hjl.tools@gmail.com> Date: Thu, 04 Feb 2021 11:38:42 +0100 In-Reply-To: (H. J. Lu via Libc-alpha's message of "Wed, 3 Feb 2021 07:09:40 -0800") Message-ID: <87k0rom825.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-5.8 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, URIBL_BLACK 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: 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, 04 Feb 2021 10:38:48 -0000 * H. J. Lu via Libc-alpha: > Since -march=sandybridge enables ISAs in x86-64 ISA level v3, the v3 > marker is set on libc.so. We couldn't set the needed ISA marker to v2 > since this libc won't run on all v2 machines. Technically, the v3 marker > is correct. But the resulting libc.so won't run on Sandy Brigde, which > is a v2 machine, even when libc is compiled with -march=sandybridge: The v3 marker is no better than the v2 marker because it still does not cover all Sandy Bridge features implied by -march=sandybridge. Pretty much all model-based -march= options have this effect. What's the intended effect of this change? Only require x86-64-v3 if all x86-64-v3 features are implied by the -march= setting? Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill