From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Ropert Subject: Re: Trouble using update_va_mapping Date: Mon, 13 Feb 2006 18:07:52 +0100 Message-ID: <43F0BCE8.4090107@adviseo.fr> References: <43F0AE97.7070302@adviseo.fr> <98973538f8321c2ea43f52a5231916ee@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <98973538f8321c2ea43f52a5231916ee@cl.cam.ac.uk> 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@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Keir Fraser wrote: > > On 13 Feb 2006, at 16:06, Mathieu Ropert wrote: > >> i'm trying to run a very simple domU kernel on Xen/x86_64, and i'm >> getting some trouble with update_va_mapping(): when trying to remap >> some page table entry, i find the virtual address still pointing to >> the same machine address after the return of the hypercall. > > > What machine page does 'cons' point at before update_va_mapping()? Is > it definitely a different page? > > -- Keir > "cons" is a page in the domU kernel address space. I left a 4k blank (page aligned) after the kernel entry point for this purpose. In terms of assembly code, it looks like something like this: .org 0x2000 .globl console_page console_page: .fill 256, 8, 0 and then, cons = (struct xencons_interface *) &console_page in my C code. That may sound stupid and/or lazy, but i wanted a valid virtual address easy, complexity will come after i fully understand the thing :)