Re: [Qemu-devel] [PATCH v8 3/5] nvdimm acpi: build ACPI NFIT table

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

On 11/30/2015 06:30 PM, Michael S. Tsirkin wrote:
> On Mon, Nov 16, 2015 at 06:51:01PM +0800, Xiao Guangrong wrote:
>> NFIT is defined in ACPI 6.0: 5.2.25 NVDIMM Firmware Interface Table (NFIT)
>>
>> Currently, we only support PMEM mode. Each device has 3 structures:
>> - SPA structure, defines the PMEM region info
>>
>> - MEM DEV structure, it has the @handle which is used to associate specified
>>    ACPI NVDIMM  device we will introduce in later patch.
>>    Also we can happily ignored the memory device's interleave, the real
>>    nvdimm hardware access is hidden behind host
>>
>> - DCR structure, it defines vendor ID used to associate specified vendor
>>    nvdimm driver. Since we only implement PMEM mode this time, Command
>>    window and Data window are not needed
>>
>> The NVDIMM functionality is controlled by the parameter, 'nvdimm-support',
>> is introduced for PIIX4_PM and ICH9-LPC, it is true on default and it is
>> false on 2.4 and its earlier version to keep compatibility
>
> Will need to make it false on 2.5 too.
>

Yes, 2.5 have been released now, it need to be updated. :)

> Isn't there a device that needs to be created for this
> to work?  It would be cleaned to just key off

Yes. But no nvdimm device/NFIT exists if no nvdimm device is
specified by QEMU command line.

> the device presence, then we don't need compat gunk,
> and further, people not using it don't get a
> bunch of unused AML.

I am okay to make it off on default.