Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756035AbXJVSh7 (ORCPT ); Mon, 22 Oct 2007 14:37:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753961AbXJVShu (ORCPT ); Mon, 22 Oct 2007 14:37:50 -0400 Received: from gw.goop.org ([64.81.55.164]:57301 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752580AbXJVSht (ORCPT ); Mon, 22 Oct 2007 14:37:49 -0400 Message-ID: <471CEDFD.3030603@goop.org> Date: Mon, 22 Oct 2007 11:37:49 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: Nick Piggin CC: dean gaudet , David Chinner , xfs@oss.sgi.com, Xen-devel , Linux Kernel Mailing List , Mark Williamson , =?ISO-8859-1?Q?Morten_?= =?ISO-8859-1?Q?B=F8geskov?= , xfs-masters@oss.sgi.com Subject: Re: Interaction between Xen and XFS: stray RW mappings References: <470FA7C3.90404@goop.org> <471C1A61.1010001@goop.org> <200710221439.21503.nickpiggin@yahoo.com.au> In-Reply-To: <200710221439.21503.nickpiggin@yahoo.com.au> X-Enigmail-Version: 0.95.3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1006 Lines: 25 Nick Piggin wrote: > You could call it a bug I think. I don't know much about Xen though, > whether or not it expects to be able to run an arbitrary OS kernel. > Xen's paravirtualized mode always requires a guest OS to be modified; certainly some operating systems would be very hard to make work with Xen. But you can always fall back to using shadow pagetables or full hvm (VT/SVM) mode. > Presumably, the hypervisor _could_ write protect and trap writes to > *all* page table page mappings. > Xen manages this stuff with refcounts; it doesn't maintain an rmap for these pages, so it would have to exhaustively search to do this. But aside from that, Xen never actively modifies pagetables, so this would be a new behaviour in the interface. J - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/