Re: [Qemu-devel] [PATCH 00/16] implement vNVDIMM

[Xiao Guangrong <guangrong.xiao@linux.intel.com>]

On 07/03/2015 02:11 AM, Paolo Bonzini wrote:
>
>
> On 02/07/2015 20:01, Xiao Guangrong wrote:
>>
>> Thanks for your review, Stefan and Paolo!
>>
>> On 07/02/2015 05:52 PM, Paolo Bonzini wrote:
>>>
>>>
>>> On 02/07/2015 11:20, Stefan Hajnoczi wrote:
>>>>> Currently, the NVDIMM driver has been merged into upstream Linux
>>>>> Kernel and
>>>>> this patchset tries to enable it in virtualization field
>>>>
>>>>   From a device model perspective, have you checked whether it makes
>>>> sense
>>>> to integrate nvdimms into the pc-dimm and hostmem code that is used for
>>>> memory hotplug and NUMA?
>>>>
>>>> The NVDIMM device in your patches is a completely new TYPE_DEVICE so it
>>>> doesn't share any interfaces or code with existing memory devices.
>>>> Maybe that is the right solution here because NVDIMMs have different
>>>> characteristics, but I'm not sure.
>>>
>>> The hostmem code should definitely be shared, e.g. by adding a new
>>> "file" property to the memory-backend-file class.  ivshmem can also use
>>> it---CCing Marc-Andr�.
>>
>> However, file-based memory used by NVDIMM is special, it divides the file
>> to two parts, one part is used as PMEM and another part is used to store
>> NVDIMM's configure data.
>>
>> Maybe we can introduce "end-reserved" property to reserve specified size
>> at the end of the file. Or create a new class type based on
>> memory-backend-file (named nvdimm-backend-file) class to hide this magic
>> thing?
>
> I need to read the code then. :)

Paolo, do you have any comment? :)