From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wei Liu <wei.liu2@citrix.com>
Subject: Re: [PATCH 4/4] hvmloader: add support to load extra
 ACPI tables from qemu
Date: Tue, 19 Jan 2016 11:37:22 +0000
Message-ID: <20160119113722.GU1691@citrix.com>
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To: Jan Beulich <JBeulich@suse.com>
Cc: Haozhong Zhang <haozhong.zhang@intel.com>, Kevin Tian <kevin.tian@intel.com>, Wei Liu <wei.liu2@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, xen-devel@lists.xen.org, Jun Nakajima <jun.nakajima@intel.com>, Keir Fraser <keir@xen.org>
List-Id: xen-devel@lists.xenproject.org

On Mon, Jan 18, 2016 at 01:46:29AM -0700, Jan Beulich wrote:
> >>> On 18.01.16 at 01:52, <haozhong.zhang@intel.com> wrote:
> > On 01/15/16 10:10, Jan Beulich wrote:
> >> >>> On 29.12.15 at 12:31, <haozhong.zhang@intel.com> wrote:
> >> > NVDIMM devices are detected and configured by software through
> >> > ACPI. Currently, QEMU maintains ACPI tables of vNVDIMM devices. This
> >> > patch extends the existing mechanism in hvmloader of loading passthrough
> >> > ACPI tables to load extra ACPI tables built by QEMU.
> >> 
> >> Mechanically the patch looks okay, but whether it's actually needed
> >> depends on whether indeed we want NV RAM managed in qemu
> >> instead of in the hypervisor (where imo it belongs); I didn' see any
> >> reply yet to that same comment of mine made (iirc) in the context
> >> of another patch.
> > 
> > One purpose of this patch series is to provide vNVDIMM backed by host
> > NVDIMM devices. It requires some drivers to detect and manage host
> > NVDIMM devices (including parsing ACPI, managing labels, etc.) that
> > are not trivial, so I leave this work to the dom0 linux. Current Linux
> > kernel abstract NVDIMM devices as block devices (/dev/pmemXX). QEMU
> > then mmaps them into certain range of dom0's address space and asks
> > Xen hypervisor to map that range of address space to a domU.
> > 

OOI Do we have a viable solution to do all these non-trivial things in
core hypervisor?  Are you proposing designing a new set of hypercalls
for NVDIMM?  

Wei.