Re: [PATCH v2 08/22] memblock: Introduce a generic phys_addr_to_target_node()

[Dan Williams]

On Mon, Jul 13, 2020 at 12:04 AM Mike Rapoport <rppt@xxxxxxxxxxxxx> wrote:
>
> Hi Dan,
>
> On Sun, Jul 12, 2020 at 09:26:48AM -0700, Dan Williams wrote:
> > Similar to how generic memory_add_physaddr_to_nid() interrogates
> > memblock data for numa information, introduce
> > get_reserved_pfn_range_from_nid() to enable the same operation for
> > reserved memory ranges. Example memory ranges that are reserved, but
> > still have associated numa-info are persistent memory or Soft Reserved
> > (EFI_MEMORY_SP) memory.
>
> Here again, I would prefer to add a weak default for
> phys_to_target_node() because the "generic" implementation is not really
> generic.
>
> The fallback to reserved ranges is x86 specfic because on x86 most of the
> reserved areas is not in memblock.memory. AFAIK, no other architecture
> does this.

True, I was pre-fetching ARM using the new EFI "Special Purpose"
memory attribute. However, until that becomes something that platforms
deploy in practice I'm ok with not solving that problem for now.

> And x86 anyway has implementation of phys_to_target_node().

Sure, let's go with the default stub for non-x86.

Justin, do you think it would make sense to fold your dax_kmem
enabling for arm64 series into my enabling of dax_hmem for all
memory-hotplug archs?