From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id E9D5A1F5AE for ; Fri, 26 Jun 2020 21:24:34 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id D210D388C031; Fri, 26 Jun 2020 21:24:33 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D210D388C031 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1593206673; bh=AXmOwqCJmqotL48vHIEqiDk7W40IV6Kbx2CSGVeowJU=; h=To:Subject:References:Date:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=dxv9U9g34/d9zak3tbyGB1D0rdIx+6nus8hYY+NhlgJ16a2LJnbhBoDdn8xgN230z sZ0q94qxoXQMQjsw7JYDwpcmdBBHpIhNNWMV7rawXzSXFpMMCJ9uhNyodiHI4cqbTL bSzchrvW7eLMYFQLBueSUs+Ucug7vxnlf9UrawIk= 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) To: Carlos O'Donell 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-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: , From: Florian Weimer via Libc-alpha Reply-To: Florian Weimer Cc: Pedro Alves , Daniel Walker via Libc-alpha , Conan C Huang , Jeremy Stenglein , xe-linux-external@cisco.com Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" * 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