libvirt users - Jul 2017 - cannot set maxMemory

Hi all,

I'm testing the memory hotplugging on devstack (ocata version).

According to the article in
https://medium.com/@juergen_thomann/memory-hotplug-with-qemu-kvm-and-libvirt-558f1c635972
,
I'm trying to create a virtual machine by setting <maxMemory>.
However, I've got an error message in libvirt log as below.

2017-07-20 20:33:21.175+0000: 529: error :
virDomainDefCheckUnsupportedMemoryHotplug:1192 : unsupported configuration:
memory hotplug tunables <maxMemory> are not supported by this hypervisor
driver
virt-aa-helper: error: could not parse XML
virt-aa-helper: error: could not get VM definition

I'm using qemu hypervisor (2.8), and libvirt (2.5.0).
As I know, these qemu, libvirt versions support hotplugging memory.
Below is the xml file I used to create a virtual machine by using 'virsh
create test.xml' command.

<domain type='qemu'>
  <name>QEmu-fedora-i686</name>
  <uuid>c7a5fdbd-cdaf-9455-926a-d65c16db1809</uuid>
  <maxMemory slots='4'
unit='KiB'>2097152</maxMemory>
  <memory>219200</memory>
  <currentMemory>219200</currentMemory>
  <vcpu>2</vcpu>
  <cpu>
    <numa>
      <cell id="0" cpus="0" memory="2097152"
unit="KiB"/>
    </numa>
  </cpu>
  <driver name="qemu" type="qcow2"
cache="none"/>
  <os>
    <type arch='i686' machine='pc'>hvm</type>
    <boot dev='cdrom'/>
  </os>
  <devices>
    <emulator>/usr/bin/qemu-system-ppc</emulator>
    <disk type='file' device='cdrom'>
      <source file='/home/user/boot.iso'/>
      <target dev='hdc'/>
      <readonly/>
    </disk>
    <disk type='file' device='disk'>
      <source file='/home/user/fedora.img'/>
      <target dev='hda'/>
    </disk>
    <interface type='network'>
      <source network='default'/>
    </interface>
  </devices>
</domain>

Does anyone know the reason?

Thanks,
Youngbin