From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43786) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VReC8-0003fK-5o for qemu-devel@nongnu.org; Thu, 03 Oct 2013 04:23:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VReBx-0000uz-Br for qemu-devel@nongnu.org; Thu, 03 Oct 2013 04:23:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11261) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VReBx-0000tf-46 for qemu-devel@nongnu.org; Thu, 03 Oct 2013 04:23:25 -0400 Message-ID: <524D2985.8050301@redhat.com> Date: Thu, 03 Oct 2013 10:23:33 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1380119568-5530-1-git-send-email-lilei@linux.vnet.ibm.com> <5242FAE8.6030807@redhat.com> <52442C16.7000200@linux.vnet.ibm.com> <524CEC9A.6050602@linux.vnet.ibm.com> In-Reply-To: <524CEC9A.6050602@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/8 RFC] migration: Introduce side channel for RAM List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Lei Li Cc: aarcange@redhat.com, quintela@redhat.com, mdroth@linux.vnet.ibm.com, mrhines@linux.vnet.ibm.com, qemu-devel@nongnu.org, anthony@codemonkey.ws, lagarcia@br.ibm.com, rcj@linux.vnet.ibm.com Il 03/10/2013 06:03, Lei Li ha scritto: >>> > > Hi Paolo, > > When debugging the code, I realized that this problem might still > exist. In the incoming part, it will qemu_fopen_pipe() in > unix_accept_incoming_migration first to enable the load_hook > callback, the check action of this RAM_SAVE_FLAG_HOOK flags would > lead to 8 bytes taken. Turns out, it will break normal unix > migration (without unix-page-flipping), because no matter normal unix > migration or unix-page-flipping migration, the incoming side has to > check this 8-byes flags first to decide whether the load_hook is > called, and normal unix migration did not send this 8-byte flags. Why is the load_hook callback being called at all without page flipping? Without page flipping, the before_iterate and save_page hook will return immediately (or depending on your code they may never be called), so the RAM_SAVE_FLAG_HOOK will never be written to the Unix socket. > I wonder if I didn't understand your suggestion correctly? Perhaps you want to discuss this tomorrow morning on #qemu? Paolo