On Tue, Nov 12, 2024 at 01:28:03PM -0800, Dan Williams wrote: > 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. > > Should the advice just succeed when the result does not matter? > I figure at some point during __init the value will be probed and subsequent calls will be ignored. I'd rather fail explicitly in that case to assist debugging - otherwise it might be a little maddening to discover your callsite is too late in the process. > Otherwise, it depends on the caller to not care based on config. > > I do not feel that strongly about it, so either way: > > Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx>
