Re: [Xen-devel] [RFC Design Doc] Add vNVDIMM support for Xen

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.04.16 at 14:26, <haozhong.zhang@xxxxxxxxx> wrote:
> On 04/22/16 04:53, Jan Beulich wrote:
>> Perhaps I have got confused by the back and forth. If we're to
>> use struct page_info, then everything should be following a
>> similar flow to what happens for normal RAM, i.e. normal page
>> allocation, and normal assignment of pages to guests.
>>
> 
> I'll follow the normal assignment of pages to guests for pmem, but not
> the normal page allocation. Because allocation is difficult to always
> get the same pmem area for the same guest every time. It still needs
> input from others (e.g. toolstack) that can provide the exact address.

Understood.

> Because the address is now not decided by xen hypervisor, certain
> permission track is needed. For this part, we will re-use the existing
> one for MMIO. Directly using existing range struct for pmem may
> consume too much space, so I proposed to choose different data
> structures or put limitation on exiting range struct to avoid or
> mitigate this problem.

Why would these consume too much space? I'd expect there to be
just one or very few chunks, just like is the case for MMIO ranges
on devices.

Jan

> The data structure change will be applied only
> to pmem, and only the code that manipulate the range structs
> (rangeset_*) will be changed for pmem. So for the permission tracking
> part, it will still follow the exiting one.
> 
> Haozhong




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