[PATCH RFC] mm: remove CONFIG_HAVE_MEMBLOCK_NODE_MAP (was: Re: [PATCH v3 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA)

[Mike Rapoport]

On Mon, Mar 30, 2020 at 11:58:43AM +0200, Michal Hocko wrote:
> 
> What would it take to make ia64 use HAVE_MEMBLOCK_NODE_MAP? I would
> really love to see that thing go away. It is causing problems when
> people try to use memblock api.

Well, it's a small patch in the end :)

Currently all NUMA architectures currently enable
CONFIG_HAVE_MEMBLOCK_NODE_MAP and use free_area_init_nodes() to initialize
nodes and zones structures.

On the other hand, the systems that don't have
CONFIG_HAVE_MEMBLOCK_NODE_MAP use free_area_init() or free_area_init_node()
for this purpose.

With this assumptions, it's possible to make selection of the functions
that calculate spanned and absent pages at runtime.

This patch builds for arm and x86-64 and boots on qemu-system for both.