The section size defines the granularity of memory hotplug. This is currently hard coded to 1GB on arm64 linux, which defines that the least size of memblock that can be hotplugged out is 1GB. Some DDR configurations (especially low RAM and dual-rank DDRs) may have section sizes that are less than 1GB (ex. 512MB, 256MB etc.). Having an option to reduce the memblock size to section size or lower gives more granularity of memory hotplug. For example, a system with DDR section size of 512MB and kernel memblock size of 1GB, we would have to remove two segments of DDR sections in order to hotplug out atleast 1 memblock from kernel POV. Section sizes of DDRs vary based on specs (number of ranks, channels, regions etc.) Making this section size configurable helps users to assign based on the DDR being used. The default is set to 1GB which is the current memblock size. Sudarshan Rajagopalan (1): arm64: Make section size configurable for memory hotplug arch/arm64/Kconfig | 11 +++++++++++ arch/arm64/include/asm/sparsemem.h | 4 ++++ 2 files changed, 15 insertions(+) -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
