mm/memblock: export memblock_{start/end}_of_DRAM

[David Hildenbrand]

On 31.10.20 10:18, Christoph Hellwig wrote:
> On Fri, Oct 30, 2020 at 10:38:42AM +0200, Mike Rapoport wrote:
>>   
>> What do you mean by "system memory block"? There could be a lot of
>> interpretations if you take into account memory hotplug, "mem=" option,
>> reserved and firmware memory.
>>
>> I'd suggest you to describe the entire use case in more detail. Having
>> the complete picture would help finding a proper solution.
> 
> I think we need the code for the driver trying to do this as an RFC
> submission.  Everything else is rather pointless.

Sharing RFCs is most probably not what people want when developing 
advanced hypervisor features :)

@Sudarshan, I recommend looking at the slides of the KVM Forum talk from 
yesterday

https://kvmforum2020.sched.com/event/eE40/towards-an-alternative-memory-architecture-joao-martins-oracle?iframe=no

It contains a nice summary of the state of art, and how "mem=", devdax, 
and dax_hmat can be used to tackle the issue in a hypervisor.

-- 
Thanks,

David / dhildenb