Edit file File name : 40-vm-hotadd.rules Content :# On Hyper-V and Xen Virtual Machines we want to add memory and cpus as soon as they appear ATTR{[dmi/id]sys_vendor}=="Microsoft Corporation", ATTR{[dmi/id]product_name}=="Virtual Machine", GOTO="vm_hotadd_apply" ATTR{[dmi/id]sys_vendor}=="Xen", GOTO="vm_hotadd_apply" GOTO="vm_hotadd_end" LABEL="vm_hotadd_apply" # Memory hotadd request SUBSYSTEM=="memory", ACTION=="add", DEVPATH=="/devices/system/memory/memory[0-9]*", TEST=="state", ATTR{state}!="online", ATTR{state}="online" # CPU hotadd request SUBSYSTEM=="cpu", ACTION=="add", DEVPATH=="/devices/system/cpu/cpu[0-9]*", TEST=="online", ATTR{online}!="1", ATTR{online}="1" LABEL="vm_hotadd_end" Save