From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: Re: how to enable shadow page table? Do I have to run HVM guest systems for shadow paging mode? Date: Mon, 16 Mar 2009 10:06:26 -0700 Message-ID: <49BE8712.40605@goop.org> References: <20090316164824.9BE2A3400090@usps.crhc.uiuc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090316164824.9BE2A3400090@usps.crhc.uiuc.edu> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Long Wang Cc: Xen-devel , Tim Deegan List-Id: xen-devel@lists.xenproject.org Long Wang wrote: > I looked into the live migration code in Xen. I need more than the mechanism > provided in live migration, as described below: > > 1. scan the states of all the memory pages of a domain, set dirty pages as > read-only, and clear all dirty bits for all the memory pages (so read-only > and dirty are two different bits). This procedure is done periodically. > > 2. When a readonly page is to be updated by the domain, the update is > trapped into the hypervisor, when I copy the page content to another place, > and set the page as writable (this page is not a page table page), makes the > update. > > I find that the mechanism used in live migration cannot handle these. How > can I enable shadow paging in PV? If not, do I have to find a machine with > vmx-featured processor and run HVM for this machine? > Well, that's an option. But if you're going to be hacking Xen anyway, then it sounds like log-dirty is close to what you want. But Tim is probably the person to ask about that. J