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 D1B1B3893668 for ; Thu, 25 Feb 2021 16:48:50 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org D1B1B3893668 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-598-OkpuLwT8MfKpnQ_Ev7na0g-1; Thu, 25 Feb 2021 11:48:46 -0500 X-MC-Unique: OkpuLwT8MfKpnQ_Ev7na0g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5F30A180F169; Thu, 25 Feb 2021 16:48:45 +0000 (UTC) Received: from tucnak.zalov.cz (ovpn-112-197.ams2.redhat.com [10.36.112.197]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 09CA560861; Thu, 25 Feb 2021 16:48:44 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.16.1/8.16.1) with ESMTPS id 11PGmfgH1786168 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Thu, 25 Feb 2021 17:48:42 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.16.1/8.16.1/Submit) id 11PGmeYw1785950; Thu, 25 Feb 2021 17:48:40 +0100 Date: Thu, 25 Feb 2021 17:48:40 +0100 From: Jakub Jelinek To: "Frank Ch. Eigler" Cc: Tom Tromey , Mark Wielaard , dwz@sourceware.org, elfutils-devel@sourceware.org, gdb-patches@sourceware.org Subject: Re: build-ids, .debug_sup and other IDs Message-ID: <20210225164840.GJ4020736@tucnak> Reply-To: Jakub Jelinek References: <20210221231810.1062175-1-tom@tromey.com> <20210224150752.GA23884@tarox.wildebeest.org> <87a6rt1b12.fsf@tromey.com> <20210225164245.GC11313@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210225164245.GC11313@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-3.9 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=unavailable autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: dwz@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Dwz mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Feb 2021 16:48:51 -0000 On Thu, Feb 25, 2021 at 11:42:45AM -0500, Frank Ch. Eigler via Dwz wrote: > > FWIW I looked a little at unifying these. For example, > > bfdopncls.c:bfd_get_alt_debug_link_info could look at both the build-id > > and .debug_sup. > > > > But, this seemed a bit weird. What if both appear and they are > > different? Then a single API isn't so great -- you want to check the ID > > corresponding to whatever was in the original file. > > If both appear and are different, can we characterize the elf file as > malformed? Unsure, the DWARF spec only talks about .debug_sup, the NOTE is a GNU extension. > Does our current tooling produce such files? If it's an dwz without --dwarf-5 produces .gnu_debugaltlink in the referrers and .note.gnu.build-id in the supplemental object file. For dwz --dwarf-5, if it produced a .note.gnu.build-id, it would produce the same one, but I thought that if I produced that, then consumers could keep using that instead of .debug_sup which is the only thing defined in the standard, so in the end dwz --dwarf-5 only produces .debug_sup on both the referrers side and on the side of supplemental object file as DWARF specifies. Jakub