From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 98564 invoked by alias); 13 Feb 2019 18:47:37 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 98492 invoked by uid 89); 13 Feb 2019 18:47:37 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.2 spammy=H*i:sk:87k1i36, H*f:sk:87k1i36, talk X-HELO: mail-qt1-f175.google.com Received: from mail-qt1-f175.google.com (HELO mail-qt1-f175.google.com) (209.85.160.175) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 13 Feb 2019 18:47:36 +0000 Received: by mail-qt1-f175.google.com with SMTP id z39so3889528qtz.0 for ; Wed, 13 Feb 2019 10:47:36 -0800 (PST) Return-Path: Received: from [10.150.73.190] (76.sub-174-228-0.myvzw.com. [174.228.0.76]) by smtp.gmail.com with ESMTPSA id a185sm28327qkb.1.2019.02.13.10.47.32 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Feb 2019 10:47:33 -0800 (PST) Subject: Re: PSA: Formalizing the glibc<->gdb probe-based interface. To: Tom Tromey Cc: GNU C Library , gdb@sourceware.org References: <87k1i3628v.fsf@tromey.com> From: Carlos O'Donell Openpgp: preference=signencrypt Message-ID: <9bab99fb-fe91-f214-ccb6-c16739f8d231@redhat.com> Date: Wed, 13 Feb 2019 18:47:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <87k1i3628v.fsf@tromey.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2019-02/txt/msg00018.txt.bz2 On 2/13/19 12:13 PM, Tom Tromey wrote: >>>>>> "Carlos" == Carlos O'Donell writes: > > Carlos> We document *other* probes in manual/probes.texi, but we should > Carlos> add a section for stable guaranteed probes, and discuss a way > Carlos> to deprecate the probes should we ever need to do that. > > Because probes are introspectable, it's actually better to remove them > than to change their semantics -- the tools can adapt more easily to > this. Of course it's good to have a transition period, or at least some > sort of warning. > > As I recall we had some thoughts about ABI compatibility when adding the > probes; namely that it is ok to add arguments to the end, but not ok to > remove arguments or to change the meaning of existing arguments. Agreed. In general I think the probe name should always change if: * semantics change. * # of arguments change. Then you'll always be safe. If you can't keep implementing the probe it is safest to remove it. Talk to the users of the probe first and reach consensus :-) -- Cheers, Carlos.