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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.01.16 at 15:01, <haozhong.zhang@xxxxxxxxx> wrote:
> On 01/21/16 03:25, Jan Beulich wrote:
>> >>> On 21.01.16 at 10:10, <guangrong.xiao@xxxxxxxxxxxxxxx> wrote:
>> > b) some _DSMs control PMEM so you should filter out these kind of _DSMs and
>> >     handle them in hypervisor.
>> 
>> Not if (see above) following the model we currently have in place.
>>
> 
> You mean let dom0 linux evaluates those _DSMs and interact with
> hypervisor if necessary (e.g. XENPF_mem_hotadd for memory hotplug)?

Yes.

>> > c) hypervisor should mange PMEM resource pool and partition it to multiple
>> >     VMs.
>> 
>> Yes.
>>
> 
> But I Still do not quite understand this part: why must pmem resource
> management and partition be done in hypervisor?

Because that's where memory management belongs. And PMEM,
other than PBLK, is just another form of RAM.

> I mean if we allow the following steps of operations (for example)
> (1) partition pmem in dom 0
> (2) get address and size of each partition (part_addr, part_size)
> (3) call a hypercall like nvdimm_memory_mapping(d, part_addr, part_size, 
> gpfn) to
>     map a partition to the address gpfn in dom d.
> Only the last step requires hypervisor. Would anything be wrong if we
> allow above operations?

The main issue is that this would imo be a layering violation. I'm
sure it can be made work, but that doesn't mean that's the way
it ought to work.

Jan


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