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 [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 281AD385780B for ; Wed, 12 May 2021 08:27:08 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 281AD385780B 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-249-ThjrK9vLNDCtGllJLEh-_g-1; Wed, 12 May 2021 04:27:06 -0400 X-MC-Unique: ThjrK9vLNDCtGllJLEh-_g-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 425BB101371B; Wed, 12 May 2021 08:27:05 +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 699D81E6; Wed, 12 May 2021 08:27:04 +0000 (UTC) From: Florian Weimer To: "Lucas A. M. Magalhaes" Cc: libc-alpha@sourceware.org Subject: Re: [PATCH 2/3] powerpc64le: Check HWCAP bits against compiler build flags References: <162076753769.316372.10532385586864995177@fedora.local> Date: Wed, 12 May 2021 10:27:33 +0200 In-Reply-To: <162076753769.316372.10532385586864995177@fedora.local> (Lucas A. M. Magalhaes's message of "Tue, 11 May 2021 18:12:17 -0300") Message-ID: <87im3owe4q.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 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.1 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=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: Wed, 12 May 2021 08:27:09 -0000 * Lucas A. M. Magalhaes: > Hi Florian. I've tested this patch on POWER[8..10] with -mcpu=power9 and > -mcpu=power10 built with GCC 10.3.1. > > When built with -mcpu=power10 I got a SIGILL on POWER8 and POWER10. Do you mean POWER8 and POWER9? > For testing I'm just running ./libc.so. I try to inspect it with > gdb. With -mcpu=power9 I can see it passing through dl_hwcap_check > but not with -mcpu=power10. > > I maybe doing something wrong though. I tried to allude in the commit message that this is expected. Maybe I should drop the POWER10 check? I do not think this is fixable in the long term because I expect that POWER10 builds won't need the bootstrap relocation in the dynamic loader thanks to its PCREL instructions. (POWER10 should be PI_STATIC_AND_HIDDEN.) We could disable POWER10 code for early parts of the dynamic loader, but that will only work until we start to rely on PI_STATIC_AND_HIDDEN, which has other benefits. Thanks, Florian