From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) by sourceware.org (Postfix) with ESMTP id 1E082388C005 for ; Fri, 26 Jun 2020 21:24:32 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 1E082388C005 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-400-9Fqe-yW6NOiyHjE3mw3mGw-1; Fri, 26 Jun 2020 17:24:28 -0400 X-MC-Unique: 9Fqe-yW6NOiyHjE3mw3mGw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0F37E1005512; Fri, 26 Jun 2020 21:24:27 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-129.ams2.redhat.com [10.36.112.129]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 21F1D19C58; Fri, 26 Jun 2020 21:24:22 +0000 (UTC) From: Florian Weimer To: Carlos O'Donell Cc: Daniel Walker via Libc-alpha , Pedro Alves , xe-linux-external@cisco.com, Conan C Huang , Jeremy Stenglein Subject: Re: [RFC PATCH 3/3] add r_debug multiple namespaces support References: <20200626193228.1953-4-danielwa@cisco.com> <87ftah5yh8.fsf@oldenburg2.str.redhat.com> <210c992f-b034-3ef7-440c-f67ab1b3acdb@redhat.com> Date: Fri, 26 Jun 2020 23:24:21 +0200 In-Reply-To: <210c992f-b034-3ef7-440c-f67ab1b3acdb@redhat.com> (Carlos O'Donell's message of "Fri, 26 Jun 2020 17:19:27 -0400") Message-ID: <87366h5xmi.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.9 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP 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: Fri, 26 Jun 2020 21:24:33 -0000 * Carlos O'Donell: > On 6/26/20 5:05 PM, Florian Weimer via Libc-alpha wrote: >> * Daniel Walker via Libc-alpha: >> >>> diff --git a/elf/link.h b/elf/link.h >>> index 0048ad5d4d..5a42511636 100644 >>> --- a/elf/link.h >>> +++ b/elf/link.h >>> @@ -61,6 +61,10 @@ struct r_debug >>> } r_state; >>> >>> ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */ >>> + >>> + /* Link to next r_debug struct. Each r_debug struct represents a >>> + different namespace. The first r_debug struct is the default. */ >>> + struct r_debug *next; >>> }; >>> >>> /* This is the instance of that structure used by the dynamic linker. */ >> >> How has this patch been tested? I expect that it will cause an abilist >> mismatch for the _r_debug symbol in the dynamic linker. >> >> If we go this route to add this capability, I think we have to add a new >> symbol version for the _r_debug symbol, and keep the old one at the >> previous size. >> >> How is your compatibility experience with the size and version change? >> How many tools need updating before they work again? >> >> A different approach would add another symbol (parallel to _r_debug) to >> store this data. This would avoid the need for any immediate tool >> updates. > > I mention this in my response to the cover letter in this series. Your explanation there was truncated. > This patch is probably unacceptable as-is because of application > expectations. But perhaps Cisco's experience shows that our worries are unfounded? Thanks, Florian