Hi, I'd like to try the memory hot unplug, refer to: https://www.ovirt.org/documentation/vmm-guide/chap-Editing_Virtual_Machines....: "All blocks of the hot-plugged memory must be set to **online_movable** in the virtual machine’s device management rules. In virtual machines running up-to-date versions of Enterprise Linux or CoreOS, this rule is set by default." I created a VM running CentOS7.6: # more /etc/redhat-release CentOS Linux release 7.6.1810 (Core) # more /usr/lib/udev/rules.d/40-redhat.rules ... # Memory hotadd request SUBSYSTEM!="memory", ACTION!="add", GOTO="memory_hotplug_end" PROGRAM="/bin/uname -p", RESULT=="s390*", GOTO="memory_hotplug_end" ENV{.state}="online" PROGRAM="/bin/systemd-detect-virt", RESULT=="none", ENV{.state}="online_movable" ATTR{state}=="offline", ATTR{state}="$env{.state}" LABEL="memory_hotplug_end" It looks like the online_movable will be set only when systemd-detect-virt returns none, i.e. hot plugging memory for a bare-metal machine, so how to make the hot plugged memory "online_movable" in the virtual machines? Thank you. Regards, -Zhen