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 7DD38385381D for ; Tue, 3 Aug 2021 18:12:33 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 7DD38385381D 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-261-kQKWPLDfNrac8qe328SIUw-1; Tue, 03 Aug 2021 14:12:31 -0400 X-MC-Unique: kQKWPLDfNrac8qe328SIUw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 18B9A107ACF5; Tue, 3 Aug 2021 18:12:30 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.123]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5AD035D9DC; Tue, 3 Aug 2021 18:12:24 +0000 (UTC) From: Florian Weimer To: Daniel Walker Cc: "H.J. Lu" , "Metzger, Markus T" , "Carlos O'Donell via Libc-alpha" , Pedro Alves , Conan C Huang , Jeremy Stenglein , "xe-linux-external(mailer list)" Subject: Re: RFC: Add DT_GNU_DEBUG References: <20210727173958.GB1633923@zorba> <20210728154408.GF1633923@zorba> <20210728190211.GJ1633923@zorba> <87o8agto7v.fsf@oldenburg.str.redhat.com> <20210803163917.GU1633923@zorba> Date: Tue, 03 Aug 2021 20:12:22 +0200 In-Reply-To: <20210803163917.GU1633923@zorba> (Daniel Walker's message of "Tue, 3 Aug 2021 09:39:17 -0700") Message-ID: <87mtpyfldl.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 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-6.9 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_H3, 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: Tue, 03 Aug 2021 18:12:35 -0000 * Daniel Walker: > On Mon, Aug 02, 2021 at 06:10:55AM -0700, H.J. Lu wrote: >> On Sun, Aug 1, 2021 at 10:22 PM Florian Weimer wrot= e: >> > >> > * H. J. Lu: >> > >> > > On Wed, Jul 28, 2021 at 1:04 PM H.J. Lu wrote: >> > >> > Do you want to drive this, or should I ? It looks like you know t= he people >> > >> > involved better than I do. >> > >> > >> > >> >> > >> https://groups.google.com/g/generic-abi/c/1ngxmSwrafc >> > >> >> > > >> > > I don't think the gABI community is interested in a new debug dynami= c >> > > tag. I propose DT_GNU_DEBUG: >> > > >> > > #define DT_GNU_DEBUG 0x6ffffff8 >> > > >> > > for the address of a pointer which will be filled by the dynamic >> > > linker. Linker should >> > > add the DT_GNU_DEBUG entry to executable's dynamic section. >> > > >> > > BTW, we have a choice. DT_GNU_DEBUG can be readonly or readonly aft= er >> > > relocation, like DT_DEBUG. >> > >> > What about adding DT_DEBUG_SIZE, specifying the size of the data point= ed >> > to by DT_DEBUG? >>=20 >> It works if we don't need to support static executables. >>=20 >> > Perhaps the gABI folks are interested in that, too? I think it's wort= h >> > a try. If the answer is =E2=80=9Cno=E2=80=9D, we can still add DT_GNU= _DEBUG_SIZE to the >> > GNU ABI. >>=20 >> I did. I didn't get any feedback. > > So no feedback equal "not interested" ? I think the issue is that the struct already has a version field. It's only a problem for us because we have architectures with copy relocations *and* have exposed _r_debug as a public symbol. However, we can do what we did for _sys_errlist in the past (new symbol versions for each size change), so it's not a real blocker. I suppose the easiest way forward would be to grow _r_debug this way, bump the version field past Solaris' version, add the Solaris members (possibly with dummy values), and add our own new stuff afterwards. Thanks, Florian