[PATCH 4/6] Have x86_64 use add_active_range() and free_area_init_nodes

[Mika Penttilä]

>
> Right, it's all very clear now. At some point in the future, I'd like 
> to visit why SPARSEMEM-based hot-add is not always used but it's a 
> separate issue.
>
>> The add areas
>> are marked as RESERVED during boot and then later onlined during add.
>
> That explains the reserve_bootmem_node()
>
But pages are marked reserved by default. You still have to alloc the 
bootmem map for the the whole node range, including reserve hot add 
areas and areas beyond e820-end-of-ram. So all the areas are already 
reserved, until freed.

--Mika