From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: Essay on an important Xen decision (long) Date: Wed, 11 Jan 2006 10:25:08 -0600 Message-ID: <43C53164.2070308@us.ibm.com> References: <516F50407E01324991DD6D07B0531AD59030F8@cacexc12.americas.cpqcorp.net> <43C41133.3050606@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: "Magenheimer, Dan (HP Labs Fort Collins)" , xen-devel List-Id: xen-devel@lists.xenproject.org Hi Keir, Keir Fraser wrote: > > On an architecture where VP is cheaper to implement than on x86, it > may well make sense to do that in preference to P2M. As you say, it > makes certain future extensions less of a pain to implement. Is VP on x86 expensive in terms of performance or complexity? I imagine that you would have to always have shadow paging enable but you could still do bulk updates ala writable page tables so the performance cost should be minimal I would think. Trying to understand the memory system in more details so any additional info is much appreciate :-) Thanks, Anthony Liguori > If ia64 does decide to back off from the P==M route then I suspect VP > is the way to go (which is I think how ia64 domU's currently work > anyway). > > -- Keir > >