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From: Dan Williams <dan.j.williams@intel.com>
Date: Tue, 28 Nov 2017 10:03:25 -0800
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Subject: Re: [Qemu-devel] KVM "fake DAX" flushing interface - discussion
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To: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Rik van Riel <riel@redhat.com>, Xiao Guangrong <xiaoguangrong.eric@gmail.com>, Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>, Stefan Hajnoczi <stefanha@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, kvm-devel <kvm@vger.kernel.org>, Qemu Developers <qemu-devel@nongnu.org>, "linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>, ross zwisler <ross.zwisler@linux.intel.com>, Kevin Wolf <kwolf@redhat.com>, Nitesh Narayan Lal <nilal@redhat.com>, Haozhong Zhang <haozhong.zhang@intel.com>, Ross Zwisler <ross.zwisler@intel.com>

On Fri, Nov 24, 2017 at 4:40 AM, Pankaj Gupta <pagupta@redhat.com> wrote:
[..]
> 1] Expose vNVDIMM memory range to KVM guest.
>
>    - Add flag in ACPI NFIT table for this new memory type. Do we need NVDIMM spec
>      changes for this?

Not a flag, but a new "Address Range Type GUID". See section "5.2.25.2
System Physical Address (SPA) Range Structure" in the ACPI 6.2A
specification. Since it is a GUID we could define a Linux specific
type for this case, but spec changes would allow non-Linux hypervisors
to advertise a standard interface to guests.