From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23741 invoked by alias); 8 Jun 2016 06:41:25 -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 23728 invoked by uid 89); 8 Jun 2016 06:41:23 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.9 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 spammy=Stopping, Hx-languages-length:1714, commercial, Tel X-HELO: mga04.intel.com Received: from mga04.intel.com (HELO mga04.intel.com) (192.55.52.120) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 08 Jun 2016 06:41:13 +0000 Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP; 07 Jun 2016 23:41:12 -0700 X-ExtLoop1: 1 Received: from irsmsx107.ger.corp.intel.com ([163.33.3.99]) by orsmga001.jf.intel.com with ESMTP; 07 Jun 2016 23:41:11 -0700 Received: from irsmsx104.ger.corp.intel.com ([169.254.5.117]) by IRSMSX107.ger.corp.intel.com ([169.254.10.96]) with mapi id 14.03.0248.002; Wed, 8 Jun 2016 07:41:10 +0100 From: "Metzger, Markus T" To: Marc Khouzam , "gdb@sourceware.org" Subject: RE: Stopping reverse debugging behaves differently with btrace Date: Wed, 08 Jun 2016 06:41:00 -0000 Message-ID: References: In-Reply-To: Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes X-SW-Source: 2016-06/txt/msg00006.txt.bz2 Hi Marc, > I noticed a difference of behaviour when stopping reverse debugging > with btrace vs record/replay (full mode). >=20 > If full mode, if I step to line 200 and then back to line 150 then give > the record stop command, real execution will start from line 150 as > I step my program. (This is really cool btw.) >=20 > In btrace mode (I tried bts), after I step back to line 150 and send > the record stop command, GDB appears to still be at line 150 but on > the next step, execution jumps to line 200 before doing the step > operation. >=20 > I'm guessing this has to do with the fact that btrace does not store > registers and memory, so cannot restart execution just anywhere. That's correct. > I find it strange though that when turning off record, every indication > to the user is that we are still at line 150, when in reality, GDB is > effectively back at line 200. This is particularly noticeable in a > frontends when execution jumps (unexpectedly) when the first step > is requested. >=20 > Variables also remain unavailable until the next step (or strangely, > until I send some register command). >=20 > I was wondering if GDB should reset its execution to the proper > place upon a 'record stop' for btrace? And notify the frontend of > that change. I agree. I'll look into it. Thanks for pointing it out. Regards, Markus. Intel Deutschland GmbH Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany Tel: +49 89 99 8853-0, www.intel.de Managing Directors: Christin Eisenschmid, Christian Lamprechter Chairperson of the Supervisory Board: Nicole Lau Registered Office: Munich Commercial Register: Amtsgericht Muenchen HRB 186928