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 ESMTPS id 152C43858400 for ; Tue, 14 Dec 2021 09:18:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 152C43858400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-480-TXBHcgzjPGyaE22YbZWITw-1; Tue, 14 Dec 2021 04:18:12 -0500 X-MC-Unique: TXBHcgzjPGyaE22YbZWITw-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 AF3DB81EE60; Tue, 14 Dec 2021 09:18:11 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.2.17.223]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D60BD5E26B; Tue, 14 Dec 2021 09:18:10 +0000 (UTC) From: Florian Weimer To: =?utf-8?B?RsSBbmctcnXDrCBTw7JuZw==?= Cc: Adhemerval Zanella , GNU C Library Subject: Re: [PATCH] elf: Add elf checks for main executable References: <20211119150329.2200675-1-adhemerval.zanella@linaro.org> <87bl1tmtxz.fsf@oldenburg.str.redhat.com> <873a6969-8c06-5233-2b4c-48360e120f07@linaro.org> <877dchlbb8.fsf@oldenburg.str.redhat.com> <6386c389-086d-e123-d4d6-a97777f207ed@linaro.org> <87czm8quz3.fsf@oldenburg.str.redhat.com> <871r2nmmaf.fsf@oldenburg.str.redhat.com> <20211214001742.lbleuljd2dgmfinx@google.com> <87sfuvsgll.fsf@oldenburg.str.redhat.com> Date: Tue, 14 Dec 2021 10:18:07 +0100 In-Reply-To: (=?utf-8?B?IkbEgW5nLXJ1w6wgU8OybmciJ3M=?= message of "Tue, 14 Dec 2021 01:09:40 -0800") Message-ID: <87h7bbsfxs.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=-6.5 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_H2, 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, 14 Dec 2021 09:18:17 -0000 * F=C4=81ng-ru=C3=AC S=C3=B2ng: > On Tue, Dec 14, 2021 at 1:03 AM Florian Weimer wrote= : >> >> * F=C4=81ng-ru=C3=AC S=C3=B2ng: >> >> > If the question is: "if upstream glibc implements the diagnostic, will >> > ChromeOS port the patch to their glibc". My reply is non-authoritativ= e, >> > but if this has not been a problem for more than 3 years now, I do kno= w >> > see large value backporting the feature to their older glibc release. >> >> But if you don't backport, you can teach your toolchain to start >> producing binaries that fail to load on older glibc. You will have to >> keep creating binaries that lack proper markup. >> >> My concern is that we go through all this trouble to implement a version >> proper handshake, and yet Google binaries will still crash on older >> glibc. > > 3+ years ago, "still crash on older glibc" was considered an > acceptable compromise as the scenario (cared by some upstream glibc > folks) is simply unsupported (and by many other groups). > > Now after 3 years, (while this is unsupported) back porting RELR > executables to less-than-3 year old ChromeOS would still work because > all glibc releases in the past 3 years support RELR. If you consider > symbol versioning, many symbols get new symbols which won't run on > 3-year-old glibc anyway. I have a feeling we are talking past each other. Based on previous mail exchanges, I think you would use an lld option to build binaries which use DT_RELR but do not have any version lockout for older glibc (so that these binaries still work on your older glibc with DT_RELR). Thanks, Florian