From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26949 invoked by alias); 21 May 2005 00:05:34 -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 26856 invoked from network); 21 May 2005 00:05:22 -0000 Received: from unknown (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org with SMTP; 21 May 2005 00:05:22 -0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.12.11/8.12.11) with ESMTP id j4L05L6S009391 for ; Fri, 20 May 2005 20:05:21 -0400 Received: from pobox.toronto.redhat.com (pobox.toronto.redhat.com [172.16.14.4]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id j4L05GO05048; Fri, 20 May 2005 20:05:16 -0400 Received: from touchme.toronto.redhat.com (IDENT:postfix@touchme.toronto.redhat.com [172.16.14.9]) by pobox.toronto.redhat.com (8.12.8/8.12.8) with ESMTP id j4L05DMX022924; Fri, 20 May 2005 20:05:16 -0400 Received: from tooth.toronto.redhat.com (tooth.toronto.redhat.com [172.16.14.29]) by touchme.toronto.redhat.com (Postfix) with ESMTP id B43F0800104; Fri, 20 May 2005 20:05:13 -0400 (EDT) Received: from tooth.toronto.redhat.com (IDENT:iY4d/3PcC602mcVGJ12Sj1mv4TT6/bMy@localhost [127.0.0.1]) by tooth.toronto.redhat.com (8.12.8/8.12.8) with ESMTP id j4L05DdS021027; Fri, 20 May 2005 20:05:13 -0400 Received: (from fche@localhost) by tooth.toronto.redhat.com (8.12.8/8.12.8/Submit) id j4L05Dgq021023; Fri, 20 May 2005 20:05:13 -0400 X-Authentication-Warning: tooth.toronto.redhat.com: fche set sender to fche@redhat.com using -f To: Daniel Jacobowitz Cc: Dan Shearer , gdb@sources.redhat.com Subject: Re: [discuss] Support for reverse-execution References: <20050516174649.GM19642@erizo.shearer.org> <20050520181515.GC2499@nevyn.them.org> X-Hashcash: 1:20:050521:drow@false.org::xDn/MXrIruae3JnE:00000000000000000000000000000000000000000000000CgQe X-Hashcash: 1:20:050521:dan@shearer.org::YuaY65WVXIT98UFf:00000000000000000000000000000000000000000000003MXV X-Hashcash: 1:20:050521:gdb@sources.redhat.com::6wRG+j21xyOOFWG+:0000000000000000000000000000000000000001SE/ From: fche@redhat.com (Frank Ch. Eigler) Date: Sat, 21 May 2005 00:05:00 -0000 In-Reply-To: <20050520181515.GC2499@nevyn.them.org> Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2005-05/txt/msg00252.txt.bz2 Daniel Jacobowitz writes: > On Tue, May 17, 2005 at 03:16:49AM +0930, Dan Shearer wrote: > > Around 1999 Cygnus' GPL SID simulator could execute backwards. > > Development on reversibility didn't continue so I'm told because it was > > seen as "party tricks". [...] > > Does anyone else know the history of this - was any of this code in the > version of sid in the src repository? Is any of it still there? [...] sid provides the same sort of state save/restore facility that any moderately sophisticated but not brilliant target would be able to, like ordinary simulators and even UNIX kernels with process checkpoint support. sid does not perform single-stepping backward as a primitive, since that is very complex in the general case (thus requiring a "brilliant" particular proprietary simulator). The point of the other simulation gentleman on this thread is that by using state snapshots as the basic target-side primitive, one can implement backward stepping on the gdb side in a way that will work even with non-brilliant targets. (By the way, this does not require actual bulk transmission of the state snapshots to gdb, just some sort of management protocol.) - FChE