From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29312 invoked by alias); 20 Sep 2005 22:56:30 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 28725 invoked by uid 22791); 20 Sep 2005 22:56:13 -0000 Received: from sj-iport-3-in.cisco.com (HELO sj-iport-3.cisco.com) (171.71.176.72) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Tue, 20 Sep 2005 22:56:13 +0000 Received: from sj-core-1.cisco.com ([171.71.177.237]) by sj-iport-3.cisco.com with ESMTP; 20 Sep 2005 15:56:11 -0700 X-IronPort-AV: i="3.97,128,1125903600"; d="scan'208"; a="343718831:sNHT30348990" Received: from xbh-sjc-211.amer.cisco.com (xbh-sjc-211.cisco.com [171.70.151.144]) by sj-core-1.cisco.com (8.12.10/8.12.6) with ESMTP id j8KMu350019691; Tue, 20 Sep 2005 15:56:07 -0700 (PDT) Received: from xfe-sjc-211.amer.cisco.com ([171.70.151.174]) by xbh-sjc-211.amer.cisco.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 20 Sep 2005 15:56:08 -0700 Received: from [128.107.165.235] ([128.107.165.235]) by xfe-sjc-211.amer.cisco.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 20 Sep 2005 15:56:07 -0700 Message-ID: <43309387.4020504@cisco.com> Date: Tue, 20 Sep 2005 22:56:00 -0000 From: Michael Snyder User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040929 MIME-Version: 1.0 To: gdb@sources.redhat.com CC: shebs@apple.com Subject: Re: Using reverse execution Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2005-09/txt/msg00146.txt.bz2 >>> As a comparison, for tracepoints we came up with various >>> scenarios for how they would be amazingly useful and powerful, >>> and yet after nearly a decade they remain a curiosity in GDB. >> >> IMHO, tracepoints remain a curiosity because they were never >> implemented on a large enough number of platforms. Lack of >> native support, in particular, is the main reason for its non-use. > > But don't you think it's telling that not one single person > was willing to go to the trouble of implementing it on more > platforms? When breakpoints don't work on a platform, users > don't say "oh well, we'll just have to do without". Apparently > tracepoints are just not a must-have. Eli remarked that the usefulness of reverse execution was a no-brainer for him, and it's obviously a no-brainer for you and me and a number of other GDB maintainers. And yet -- I have a target audience of engineers to whom I've been trying to "sell" reverse execution -- and I have a working implementation that I can demo, live, and a real-life bug that I can show to be easy to debug with reverse execution, and pretty damn hard otherwise. And the majority of them will go "wow", but they aren't jumping up and down demanding access to this cool facility. I think this is a familiar concept to us, but an unfamiliar one for many users, and they may have to get their hands on it and actually use it and play with it before they start to get a feel for its true power. The same may have been true for tracepoints. There were some people who went "wow", and even a few who took a stab at doing a target implementation -- but few people ever actually got to get their hands on it and play with it. Even a live demo is not always as convincing as that.