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Subject: Re: [virtio-dev] Re: [RFC] virtio-pmem: PMEM device spec
> >>>> --- /dev/null > >>>> +++ b/virtio-pmem.tex > >>>> @@ -0,0 +1,134 @@ > >>>> +\section{PMEM Device}\label{sec:Device Types / PMEM Device} > >>>> + > >>>> +The virtio pmem is a fake persistent memory (NVDIMM) device > >>>> +used to bypass the guest page cache and provide a virtio > >>>> +based asynchronous flush mechanism. This avoids the need > >>> > >>> Is there anything "fake" about virtio-pmem from the perspective of the > >>> device interface? > >>> > >>> What you are describing is one use case. But on a platform that doesn't > >>> have existing physical NVDIMM interfaces, ACPI, etc maybe virtio-pmem > >>> would be used to pass through physical NVDIMMs from the host? If you > >>> agree, then it might make sense to describe the device simply as a > >>> persistent memory device and give "fake NVDIMM" as an example use case > >>> in a separate paragraph. This would make the text more future-proof. > >> > >> Very good point. E.g. on x86-64, we might want to pass a real NVDIMM to > >> the guest using virtio-pmem, if our guest VM e.g. has no ACPI configured. > >> > >> In this case, it would be helpful to indicate if the flushing interface > >> is to be used, or if other flushing (e.g. like NVDIMMs) is to be used. > >> > > > > Yes. Agree. This is a very good point, will consider pass-through of > > real NVDIMM device for architectures don't support ACPI. > > > > Yes, corresponding flushing mechanism should be mentioned but I am not sure > > if it should be mentioned in device specification? > > Well there has to be a way to indicate how to flush writes, no? yes. Thanks, Pankaj
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