As assumed this can be triggered on x86 as well:
<maxMemory slots='4' unit='KiB'>2097152</maxMemory>
<memory unit='KiB'>524288</memory>
<currentMemory unit='KiB'>524288</currentMemory>
...
<cpu>
<numa>
<cell id='0' cpus='0' memory='524288' unit='KiB'/>
</numa>
</cpu>
root@b:~# virsh attach-device b-test hp512.xml --live
error: Failed to attach device from hp512.xml
error: this function is not supported by the connection driver: virSecurityManagerSetMemoryLabel
As assumed this can be triggered on x86 as well: >2097152< /maxMemory> >524288< /memory> >524288< /currentMemory>
<maxMemory slots='4' unit='KiB'
<memory unit='KiB'
<currentMemory unit='KiB'
...
<cpu>
<numa>
<cell id='0' cpus='0' memory='524288' unit='KiB'/>
</numa>
</cpu>
hp512m.xml
<size unit='KiB' >524288< /size>
<node> 0</node>
<memory model='dimm'>
<target>
</target>
</memory>
root@b:~# virsh attach-device b-test hp512.xml --live gerSetMemoryLab el
error: Failed to attach device from hp512.xml
error: this function is not supported by the connection driver: virSecurityMana