Re: [Qemu-devel] [PATCH v3 00/32] implement vNVDIMM

[Dan Williams]

On Mon, Oct 12, 2015 at 10:49 PM, Xiao Guangrong
<address@hidden> wrote:
>
>
> On 10/13/2015 11:38 AM, Dan Williams wrote:
>>
>> On Mon, Oct 12, 2015 at 8:14 PM, Xiao Guangrong
>> <address@hidden> 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