From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O6fso-0004jt-2Q for qemu-devel@nongnu.org; Tue, 27 Apr 2010 04:11:06 -0400 Received: from [140.186.70.92] (port=41014 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O6fsm-0004jd-Mt for qemu-devel@nongnu.org; Tue, 27 Apr 2010 04:11:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O6fsk-0005fv-Q6 for qemu-devel@nongnu.org; Tue, 27 Apr 2010 04:11:04 -0400 Received: from goliath.siemens.de ([192.35.17.28]:23820) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O6fsk-0005dU-B5 for qemu-devel@nongnu.org; Tue, 27 Apr 2010 04:11:02 -0400 Message-ID: <4BD69C10.50606@siemens.com> Date: Tue, 27 Apr 2010 10:10:56 +0200 From: Jan Kiszka MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: Problem with watchpoint in gdbstub List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jun Koi Cc: qemu-devel@nongnu.org Jun Koi wrote: > Hi, > > I am trying to debug a VM using gdb. I connected gdb to Qemu (latest > code from git repo), and issued below command: > > ... > (gdb) watch *0x77f44cd8 > (gdb) c > > The idea is to catch the write access to address 0x77f44cd8. > > But after the "c" command, I saw that the window title of my VM > continuously flip between "QEMU [Stopped]" and "QEMU", non-stop. > This makes the VM unusable. > > Is it a bug? Anybody sees the same problem? I would bet your watchpoint was established by gdb as a software watchpoint. In that case gdb will step through the target, checking after each instruction if the memory changed. Is that address valid at the time gdb wants to install it? I saw gdb choosing a software watchpoint before when it wasn't. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux