From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29471 invoked by alias); 16 Dec 2013 12:57:34 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 29458 invoked by uid 89); 16 Dec 2013 12:57:33 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.4 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mga09.intel.com Received: from mga09.intel.com (HELO mga09.intel.com) (134.134.136.24) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 16 Dec 2013 12:57:33 +0000 Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP; 16 Dec 2013 04:53:43 -0800 X-ExtLoop1: 1 Received: from irsmsx101.ger.corp.intel.com ([163.33.3.153]) by orsmga002.jf.intel.com with ESMTP; 16 Dec 2013 04:57:26 -0800 Received: from irsmsx151.ger.corp.intel.com (163.33.192.59) by IRSMSX101.ger.corp.intel.com (163.33.3.153) with Microsoft SMTP Server (TLS) id 14.3.123.3; Mon, 16 Dec 2013 12:56:31 +0000 Received: from irsmsx104.ger.corp.intel.com ([169.254.5.135]) by IRSMSX151.ger.corp.intel.com ([169.254.4.126]) with mapi id 14.03.0123.003; Mon, 16 Dec 2013 12:56:31 +0000 From: "Metzger, Markus T" To: Pedro Alves CC: "jan.kratochvil@redhat.com" , "gdb-patches@sourceware.org" Subject: RE: [patch v8 23/24] record-btrace: show trace from enable location Date: Mon, 16 Dec 2013 12:57:00 -0000 Message-ID: References: <1386839747-8860-1-git-send-email-markus.t.metzger@intel.com> <1386839747-8860-24-git-send-email-markus.t.metzger@intel.com> <52AB64F3.3010305@redhat.com> In-Reply-To: <52AB64F3.3010305@redhat.com> Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes X-SW-Source: 2013-12/txt/msg00571.txt.bz2 > -----Original Message----- > From: Pedro Alves [mailto:palves@redhat.com] > Sent: Friday, December 13, 2013 8:50 PM > > After adding incremental updates, we can now add a dummy record for the > current > > PC when we enable tracing so we show the trace from the location where > branch > > tracing has been enabled. >=20 > Ah, awesome, I was just wondering about that. :-) >=20 > I suppose one can we still access the registers when > inspecting this dummy location, or are the btrace unwinders > preventing that? You can not access registers when you are in the execution history. When we add this dummy record when we enable tracing, you're still outside the execution history, so you can access registers. Also the last instruction will be skipped for all record operations - it corresponds to the current PC and the instruction has not been executed yet. But it allows us to stitch the first trace chunk to this dummy record and thus show the full trace from the enable location. Internally, you're at the same PC if you are replaying and the replay position is at the last instruction or if you are not replaying. The different is that you will be able to access registers and memory only if you are not replaying. You will also have normal dward2 frames in that case. If you are replaying, you will have btrace frames and you won't be able to access all registers and memory. In record commands, we stop replaying once we reach the last instruction. Regards, Markus. Intel GmbH Dornacher Strasse 1 85622 Feldkirchen/Muenchen, Deutschland Sitz der Gesellschaft: Feldkirchen bei Muenchen Geschaeftsfuehrer: Christian Lamprechter, Hannes Schwaderer, Douglas Lusk Registergericht: Muenchen HRB 47456 Ust.-IdNr./VAT Registration No.: DE129385895 Citibank Frankfurt a.M. (BLZ 502 109 00) 600119052