Re: [PATCH 4/4] hvmloader: add support to load extra ACPI tables from qemu

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

On 01/21/2016 01:07 AM, Jan Beulich wrote:
>>>> On 20.01.16 at 16:29, <guangrong.xiao@linux.intel.com> wrote:
>> On 01/20/2016 07:20 PM, Jan Beulich wrote:
>>> To answer this I need to have my understanding of the partitioning
>>> being done by firmware confirmed: If that's the case, then "normal"
>>> means the part that doesn't get exposed as a block device (SSD).
>>> In any event there's no correlation to guest exposure here.
>>
>> Firmware does not manage NVDIMM. All the operations of nvdimm are handled
>> by OS.
>>
>> Actually, there are lots of things we should take into account if we move
>> the NVDIMM management to hypervisor:
>> a) ACPI NFIT interpretation
>>      A new ACPI table introduced in ACPI 6.0 is named NFIT which exports the
>>      base information of NVDIMM devices which includes PMEM info, PBLK
>>      info, nvdimm device interleave, vendor info, etc. Let me explain it one
>>      by one.
>>
>>      PMEM and PBLK are two modes to access NVDIMM devices:
>>      1) PMEM can be treated as NV-RAM which is directly mapped to CPU's address
>>         space so that CPU can r/w it directly.
>>      2) as NVDIMM has huge capability and CPU's address space is limited, NVDIMM
>>         only offers two windows which are mapped to CPU's address space, the data
>>         window and access window, so that CPU can use these two windows to access
>>         the whole NVDIMM device.
>
> You fail to mention PBLK. The question above really was about what

The 2) is PBLK.

> entity controls which of the two modes get used (and perhaps for
> which parts of the overall NVDIMM).

So i think the "normal" you mentioned is about PMEM. :)