Hi, with kernel with an obsolete version (< 3.8) DIMM configuration is not working as defined in a boot-up values, though it is possible to add dimm during runtime and it will be recognized just well. ACPI tables and the of DMI for kernels which are recognizing on-boot modules and for ones which are not are the same and I am barely remembering that some changes related to memory hotplug mechanism was landed in 3.8.
Given following configuration, dimm2 is plugged during current boot cycle of Centos 2.6.32 kernel: '{ "execute": "query-memory-devices"}' {"return":[{"type":"dimm","data":{"memdev":"/objects/mem0","hotplugged":false,"addr":4294967296,"hotpluggable":true,"size":134217728,"slot":0,"node":0,"id":"dimm0"}},{"type":"dimm","data":{"memdev":"/objects/mem1","hotplugged":true,"addr":4429185024,"hotpluggable":true,"size":134217728,"slot":1,"node":0,"id":"dimm1"}},{"type":"dimm","data":{"memdev":"/objects/mem2","hotplugged":true,"addr":4563402752,"hotpluggable":true,"size":134217728,"slot":2,"node":0,"id":"dimm2"}}],"id":"libvirt-16"} Hotplug Mem Device init_memory_mapping: 0000000110000000-0000000118000000 0110000000 - 0118000000 page 2M [ffffea0003b80000-ffffea0003d7ffff] PMD -> [ffff88001d600000-ffff88001d7fffff] on node 0 Built 1 zonelists in Node order, mobility grouping on. Total pages: 160734 Policy zone: Normal ls /sys/devices/system/memory/| grep mem memory0 memory1 memory2 memory3 memory34 ..Rebooting to 3.10.. ls /sys/devices/system/memory/| grep mem memory0 memory1 memory2 memory3 memory32 memory33 memory34 The results are based on tag-2.1.2 without any modifications.