From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hugh Dickins Subject: Re: [patch 0/6] Guest page hinting version 6. Date: Thu, 13 Mar 2008 18:55:38 +0000 (GMT) Message-ID: References: <20080312132132.520833247@de.ibm.com> <47D9754B.1030509@goop.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: <47D9754B.1030509@goop.org> Sender: linux-kernel-owner@vger.kernel.org To: Jeremy Fitzhardinge Cc: Martin Schwidefsky , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, virtualization@lists.osdl.org, akpm@linux-foundation.org, nickpiggin@yahoo.com.au, zach@vmware.com, frankeh@watson.ibm.com, rusty@rustcorp.com.au, andrea@qumranet.com, clameter@sgi.com, a.p.zijlstra@chello.nl, Keir Fraser , Ian Pratt List-Id: virtualization@lists.linuxfoundation.org On Thu, 13 Mar 2008, Jeremy Fitzhardinge wrote: > > My other concern is just correctness over time on the Linux side. We already > have enough trouble keeping things like the pte and page structure state in > sync, with resulting rare data-loss bugs. Adding another layer which only > applies in specific environments raises the possibility for new bugs to be > un-noticed for a long time. How can we structure the VM changes to make sure > that its robust in the face of maintenance? Yes, that's the main concern, as whenever lots of subtlety is added. I wonder if there's any chance of a CONFIG_DEBUG mode, which could be run on anybody's x86 machine, without involving any virtualization, but in which the PAGE_STATEs become essential to the correct working of the mm. Hugh