From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14585 invoked by alias); 21 May 2005 01:42:19 -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 14549 invoked from network); 21 May 2005 01:42:12 -0000 Received: from unknown (HELO sccrmhc12.comcast.net) (204.127.202.56) by sourceware.org with SMTP; 21 May 2005 01:42:12 -0000 Received: from [10.0.1.2] (c-24-61-199-96.hsd1.nh.comcast.net[24.61.199.96]) by comcast.net (sccrmhc12) with SMTP id <2005052101420001200baklne>; Sat, 21 May 2005 01:42:12 +0000 User-Agent: Microsoft-Entourage/11.1.0.040913 Date: Sat, 21 May 2005 01:42:00 -0000 Subject: Re: [discuss] Support for reverse-execution From: Paul Schlie To: Daniel Jacobowitz CC: Dan Shearer , Message-ID: In-Reply-To: <20050521005845.GA15974@nevyn.them.org> Mime-version: 1.0 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit X-SW-Source: 2005-05/txt/msg00254.txt.bz2 > From: Daniel Jacobowitz >> On Fri, May 20, 2005 at 06:42:45PM -0400, Paul Schlie wrote: >> - Which is fully your right to claim/believe; however noting the absence >> of non-proprietary simulators with these capabilities (it's a little >> unclear how one can presume that interfaces are likely most ideally >> necessary or appropriate; and simply note that register and memory state >> by definition is program state, which GDB already has direct access to). > > That is incorrect. There can be considerably more state. For > instance, I understand from Dan's explanation that Simics will reply > external interrupt sources - at the same clock cycles where they would > otherwise have occurred. - Supporting HW co-simulation is certainly interesting, but fundamentally no different; it only extends the definition of "state" typically by literally exposing some of the logical CPU/I/O/Peripheral/outside-world state in various levels of details depending on the goals of the model, and/or simulation itself. (but would guess likely beyond the near term goals of attempting to enable GDB support for basic reversible execution?) [And suspect you'll find that most HW savvy simulation environments have very limited if any support for "reversible" simulation, beyond checkpoint-restart. As on a cycle by cycle basis, tracking and recording incremental state changes would typically cripple the simulation, and potentially even exhaust disk storage for complex models, but limited forms do exist, and are useful.]