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

[Paolo Bonzini]

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