From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerd Knorr Subject: Re: [patch] pae: tlbflush linear page table updates Date: Tue, 9 Aug 2005 09:54:14 +0200 Message-ID: <20050809075414.GA13745@bytesex> References: <20050808145153.GA31526@bytesex> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline 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: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Mon, Aug 08, 2005 at 05:52:29PM +0100, Keir Fraser wrote: > > On 8 Aug 2005, at 15:51, Gerd Knorr wrote: > > >On l3 page dir updates (and related linear page table updates) > >we'll have to flush the tlb to make sure the linear page access > >goes to the correct pages ... > > Have you actually observed problems without the flush? Yes. PAE xenlinux (UP) didn't boot up. The first make_page_readonly() faults because the first copy_from_user() in ptwr_do_page_fault() fails (which dereferences stuff using the linear page table ...). I hoped the tlbflush also fixes the SMP issues, but it doesn't, so there are more bugs. I'm not sure the PAE/SMP crashes are ptwr related, they also happen (although a bit less likely it seems) without writable page tables. Gerd -- panic("it works"); /* avoid being flooded with debug messages */