From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31636 invoked by alias); 25 Oct 2009 01:59:26 -0000 Received: (qmail 31628 invoked by uid 22791); 25 Oct 2009 01:59:25 -0000 X-SWARE-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from smtp-outbound-2.vmware.com (HELO smtp-outbound-2.vmware.com) (65.115.85.73) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sun, 25 Oct 2009 01:59:22 +0000 Received: from mailhost3.vmware.com (mailhost3.vmware.com [10.16.27.45]) by smtp-outbound-2.vmware.com (Postfix) with ESMTP id 0496B2000E; Sat, 24 Oct 2009 18:59:21 -0700 (PDT) Received: from [10.20.94.141] (msnyder-server.eng.vmware.com [10.20.94.141]) by mailhost3.vmware.com (Postfix) with ESMTP id EB956CD9A5; Sat, 24 Oct 2009 18:59:20 -0700 (PDT) Message-ID: <4AE3AF4F.5010001@vmware.com> Date: Sun, 25 Oct 2009 02:01:00 -0000 From: Michael Snyder User-Agent: Thunderbird 1.5.0.12 (X11/20080411) MIME-Version: 1.0 To: Greg Law CC: Marc Khouzam , 'Hui Zhu' , "'gdb@sourceware.org'" Subject: Re: [FYI] tutorial for process record and reverse debugging References: <4ADA4BD8.6080800@vmware.com> <4ADCAD14.3080407@vmware.com> <4ADE1824.8090701@vmware.com> <4ADE2502.5060201@undo-software.com> <4AE34766.9060305@undo-software.com> In-Reply-To: <4AE34766.9060305@undo-software.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes 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 X-SW-Source: 2009-10/txt/msg00359.txt.bz2 Greg Law wrote: > Marc Khouzam wrote: >> >>> [...] >>>> Or do you imagine it being the default? >>>> >>> FWIW, early versions of UndoDB operated in "Marc-mode". We changed >>> it because replay mode and record are quite different, particularly >>> w.r.t. to the program's interaction with the outside world. >>> "Silent" transition from replay to record mode could be quite >>> confusing/surprising. >> In cases where the program does interact with the outside world, I >> agree that "auto-mode" could be confusing. In fact, "record mode" >> may not be the one we want in this case either. For instance, in >> some cases I may want to re-execute instructions that affect the >> outside world, even if I'm gone backwards. In this case I would want >> to use the recorded data to go backwards, but never to go forward >> (never use "replay mode"). > > I'm not completely sure of the behaviour of process record here, but > UndoDB in replay mode is completely "neutered", in that the results of > all system calls are 'synthesised'. So if, say, in record mode your > program unlinks a file, then in replay mode the fact the filename is no > longer present on the filesystem doesn't matter - we don't really do an > unlink, we just replay the results of whatever unlink returned when in > record mode. It's the same for process record.