From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacob Gorm Hansen Subject: Re: Tracking changes to writable page tables Date: Sun, 15 May 2005 01:30:50 -0700 Message-ID: <428708BA.5050205@diku.dk> References: 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: xen-devel List-Id: xen-devel@lists.xenproject.org Ian Pratt wrote: > I wander if we should steal one of the OS bits in the PTE to > differentiate writable pagetable mappings? You could then take a normal > RO fault, set the bit, and then retry to have Xen do pagetable the work. > > This would arguably be cleaner, though we've been reluctant to steal OS > bits just incase there's some OS out there that uses them all. Yes, that would also be a solution, though it is a little nasty to steal the AVL bits. Alternatively, I can just add the tracking to set_pte(), assuming that all updates come through there, but that will probably slow down page table updates a bit, even while not checkpointing the kernel. Jacob