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 D8A15385BF9B for ; Fri, 2 Jul 2021 20:43:40 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D8A15385BF9B 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-244-CmEOtJpuO4C6b-7pg8GlYg-1; Fri, 02 Jul 2021 16:43:39 -0400 X-MC-Unique: CmEOtJpuO4C6b-7pg8GlYg-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 71267102C87D; Fri, 2 Jul 2021 20:43:38 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-115-5.ams2.redhat.com [10.36.115.5]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3C7381042A97; Fri, 2 Jul 2021 20:43:37 +0000 (UTC) From: Florian Weimer To: Tulio Magno Quites Machado Filho Cc: Siddhesh Poyarekar , libc-alpha@sourceware.org Subject: Re: [PATCH v4 02/10] mtrace: Deprecate mallwatch and tr_break References: <20210702113845.3367306-1-siddhesh@sourceware.org> <20210702113845.3367306-3-siddhesh@sourceware.org> <87a6n4mozx.fsf@linux.ibm.com> Date: Fri, 02 Jul 2021 22:43:35 +0200 In-Reply-To: <87a6n4mozx.fsf@linux.ibm.com> (Tulio Magno Quites Machado Filho's message of "Fri, 02 Jul 2021 17:37:06 -0300") Message-ID: <87tulcqweg.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_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Fri, 02 Jul 2021 20:43:42 -0000 * Tulio Magno Quites Machado Filho: > Siddhesh Poyarekar via Libc-alpha writes: > >> The variable and function pair appear to provide a way for users to >> set conditional breakpoints in mtrace when a specific address is >> returned by the allocator. This can be achieved by using conditional >> breakpoints in gdb so it is redundant. There is no documentation of >> this interface in the manual either, so it appears to have been a hack >> that got added to debug malloc. Deprecate these symbols and do not >> call tr_break anymore. > > I noticed new build failures on ppc64le after this patch when using GCC 8 and 9. > > /tmp/ccg1QEe7.s: Assembler messages: > /tmp/ccg1QEe7.s: Error: `__SImallwatch_0' can't be equated to common symbol `mallwatch' > > I can't reproduce the issue when using GCC 10 or newer. Missing __attribute__ ((nocommon)). GCC 10 defaults to -fno-common. I plan to write a patch that builds glibc unconditionally with -fno-common, then the attribute won't be needed even with older GCC. Thanks, Florian