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From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver
Date: Thu, 19 Oct 2017 01:01:49 -0700
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To: Dan Williams <dan.j.williams@intel.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, Pankaj Gupta <pagupta@redhat.com>, Christoph Hellwig <hch@infradead.org>, Kevin Wolf <kwolf@redhat.com>, haozhong zhang <haozhong.zhang@intel.com>, Jan Kara <jack@suse.cz>, xiaoguangrong eric <xiaoguangrong.eric@gmail.com>, KVM list <kvm@vger.kernel.org>, David Hildenbrand <david@redhat.com>, linux-nvdimm <linux-nvdimm@ml01.01.org>, ross zwisler <ross.zwisler@intel.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Qemu Developers <qemu-devel@nongnu.org>, Linux MM <linux-mm@kvack.org>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Nitesh Narayan Lal <nilal@redhat.com>
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On Wed, Oct 18, 2017 at 08:51:37AM -0700, Dan Williams wrote:
> This use case is not "Persistent Memory". Persistent Memory is
> something you can map and make persistent with CPU instructions.
> Anything that requires a driver call is device driver managed "Shared
> Memory".

How is this any different than the existing nvdimm_flush()? If you
really care about the not driver thing it could easily be a write
to a doorbell page or a hypercall, but in the end that's just semantics.