Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753441AbcJKNIq convert rfc822-to-8bit (ORCPT ); Tue, 11 Oct 2016 09:08:46 -0400 Received: from prv-mh.provo.novell.com ([137.65.248.74]:56655 "EHLO prv-mh.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751387AbcJKNIp (ORCPT ); Tue, 11 Oct 2016 09:08:45 -0400 Message-Id: <57FCF26A02000078000F15E0@prv-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 14.2.1 Date: Tue, 11 Oct 2016 07:08:42 -0600 From: "Jan Beulich" To: Cc: , , , , , , , , , , , "Juergen Gross" , , Subject: Re: [Xen-devel] [RFC KERNEL PATCH 0/2] Add Dom0 NVDIMM support for Xen References: <20161010003523.4423-1-haozhong.zhang@intel.com> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 881 Lines: 18 >>> Andrew Cooper 10/10/16 6:44 PM >>> >On 10/10/16 01:35, Haozhong Zhang wrote: >> Xen hypervisor needs assistance from Dom0 Linux kernel for following tasks: >> 1) Reserve an area on NVDIMM devices for Xen hypervisor to place >> memory management data structures, i.e. frame table and M2P table. >> 2) Report SPA ranges of NVDIMM devices and the reserved area to Xen >> hypervisor. > >However, I can't see any justification for 1). Dom0 should not be >involved in Xen's management of its own frame table and m2p. The mfns >making up the pmem/pblk regions should be treated just like any other >MMIO regions, and be handed wholesale to dom0 by default. That precludes the use as RAM extension, and I thought earlier rounds of discussion had got everyone in agreement that at least for the pmem case we will need some control data in Xen. Jan