Re: [PATCH RFCv2 3/4] mm/memory_hotplug: Introduce and use more memory types

Michal Suchánek
2018-12-04T09:44:54Z

On Fri, 30 Nov 2018 18:59:21 +0100
David Hildenbrand <david@redhat.com> wrote:

> Let's introduce new types for different kinds of memory blocks and use
> them in existing code. As I don't see an easy way to split this up,
> do it in one hunk for now.
>
> acpi:
> Use DIMM or DIMM_UNREMOVABLE depending on hotremove support in the kernel.
> Properly change the type when trying to add memory that was already
> detected and used during boot (so this memory will correctly end up as
> "acpi" in user space).
>
> pseries:
> Use DIMM or DIMM_UNREMOVABLE depending on hotremove support in the kernel.
> As far as I see, handling like in the acpi case for existing blocks is
> not required.
>
> probed memory from user space:
> Use DIMM_UNREMOVABLE as there is no interface to get rid of this code
> again.
>
> hv_balloon,xen/balloon:
> Use BALLOON. As simple as that :)
>
> s390x/sclp:
> Use a dedicated type S390X_STANDBY as this type of memory and it's
> semantics are very s390x specific.
>
> powernv/memtrace:
> Only allow to use BOOT memory for memtrace. I consider this code in
> general dangerous, but we have to keep it working ... most probably just
> a debug feature.

I don't think it should be arbitrarily restricted like that.

Thanks

Michal