Gregory Price wrote:
> Hotplug memory sources may have opinions on what the memblock size
> should be - usually for alignment purposes. For example, CXL memory
> extents can be 256MB with a matching alignment. If this size/alignment
> is smaller than the block size, it can result in stranded capacity.
>
> Implement memory_block_advise_max_size for use prior to allocator init,
> for software to advise the system on the max block size.
>
> Implement memory_block_probe_max_size for use by arch init code to
> calculate the best block size. Use of advice is architecture defined.
>
> The probe value can never change after first probe. Calls to advise
> after probe will return -EBUSY to aid debugging.
>
> On systems without hotplug, always return -ENODEV and 0 respectively.
>
> Suggested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> Signed-off-by: Gregory Price <gourry@xxxxxxxxxx>
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>
> Acked-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
> Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Tested-by: Fan Ni <fan.ni@xxxxxxxxxxx>
> ---
[snip]
> +int __init memory_block_advise_max_size(unsigned long size)
> +{
> + if (!size || !is_power_of_2(size))
> + return -EINVAL;
> +
> + if (memory_block_advised_size_queried)
> + return -EBUSY;
> +
> + if (memory_block_advised_size) {
> + memory_block_advised_size = min(memory_block_advised_size,
> + size);
> + } else {
> + memory_block_advised_size = size;
> + }
NIT: Style: single statements don't need '{}'
Other than that it looks ok.
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
[snip]
