On Tue, Mar 11, 2025 at 12:08:03PM -0400, Zi Yan wrote: > Or a new option for memmap_on_memory like “use_whole_block”, then hotplug > code checks altmap is NULL or not when a memory block is plugged. > If altmap is NULL, the hot plugged memory block is used as memmap, > otherwise, the memory block is plugged as normal memory. The code also > needs to maintain which part of the altmap is used to tell whether > the memmap’d memory block can be offline or not. One of the first versions of memmap_on_memory did not have the restrictions of working only per memblock, so one could hot-plug more than a memory-block worth of memory using memmap_on_memory, meaning that we could end up with memblocks only containing memmap pages. Now, we decided to go with only one memblock at a time because of simplicity and also because we did not have any real-world scenarios that needed that besides being able to have larger contiguos memory for e.g: hugetlb. If people think that there is more to it, we could revisit that and see how it would look nowadays. Maybe it is not too much of a surgery. (or maybe it is :-)) -- Oscar Salvador SUSE Labs
