From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Qemu-devel] [PATCH 2/10] Allow the monitor to be suspended during non-blocking op Date: Wed, 10 Sep 2008 09:52:33 +0300 Message-ID: <48C76EB1.6040906@qumranet.com> References: <1220989802-13706-1-git-send-email-aliguori@us.ibm.com> <1220989802-13706-3-git-send-email-aliguori@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Chris Wright , Uri Lublin , Anthony Liguori , kvm@vger.kernel.org To: qemu-devel@nongnu.org Return-path: Received: from il.qumranet.com ([212.179.150.194]:15843 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751131AbYIJGwa (ORCPT ); Wed, 10 Sep 2008 02:52:30 -0400 In-Reply-To: <1220989802-13706-3-git-send-email-aliguori@us.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: Anthony Liguori wrote: > Live migration happens in the background, but it is useful to make the monitor > command appear as if it's blocking. This allows a management tool to > immediately know when the live migration has completed without having to poll > the migration status. > > This patch allows the monitor to be suspended from a monitor callback which > will prevent new monitor commands from being executed. > > This means that migration is no longer transparent. While migration is going on, you can't change the cdrom media, look at cpu registers, or do anything that requires the monitor. This both reduces the functionality and complicates management applications. IMO migration should have asynchronous notification (and no, I don't think multiple monitors is the correct solution). -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.