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From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
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Date: Wed, 14 Oct 2015 12:03:02 +0800
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Subject: Re: [Qemu-devel] [PATCH v3 00/32] implement vNVDIMM
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To: Dan Williams <dan.j.williams@intel.com>
Cc: ehabkost@redhat.com, KVM list <kvm@vger.kernel.org>, "Michael S. Tsirkin" <mst@redhat.com>, Gleb Natapov <gleb@kernel.org>, mtosatti@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, imammedo@redhat.com, Paolo Bonzini <pbonzini@redhat.com>, rth@twiddle.net



On 10/13/2015 02:36 PM, Dan Williams wrote:
> On Mon, Oct 12, 2015 at 10:49 PM, Xiao Guangrong
> <guangrong.xiao@linux.intel.com> wrote:
>>
>>
>> On 10/13/2015 11:38 AM, Dan Williams wrote:
>>>
>>> On Mon, Oct 12, 2015 at 8:14 PM, Xiao Guangrong
>>> <guangrong.xiao@linux.intel.com> wrote:
>>>>
>>>> On 10/13/2015 12:36 AM, Dan Williams wrote:
>>>>>
>>>>> Static namespaces can be emitted without a label.  Linux needs this to
>>>>> support existing "label-less" bare metal NVDIMMs.
>>>>
>>>>
>>>>
>>>> This is Linux specific? As i did not see it has been documented in the
>>>> spec...
>>>
>>>
>>> I expect most NVDIMMs, especially existing ones available today, do
>>> not have a label area.  This is not Linux specific and ACPI 6 does not
>>> specify a label area, only the Intel DSM Interface Example.
>>>
>>
>> Yup, label data is accessed via DSM interface, the spec I mentioned
>> is Intel DSM Interface Example.
>>
>> However, IIRC Linux NVDIMM driver refused to use the device if no
>> DSM GET_LABEL support, are you going to update it?
>
> Label-less DIMMs are tested as part of the unit test [1] and the
> "memmap=nn!ss" kernel parameter that registers a persistent-memory
> address range without a DIMM.  What error do you see when label
> support is disabled?
>
> [1]: https://github.com/pmem/ndctl/blob/master/README.md
>

After revert my commits on NVDIMM driver, yeah, it works.

Okay, i will drop the namespace part and make it as label-less
instead.

Thank you, Dan!