Virtualization

Running 64k guests on 4k hosts

When trying to start a VM on a host running with 4k pages, you might see the following error message:

qemu-system-ppc64: Can't support 64 kiB guest pages with 4 kiB host pages with this KVM implementation

There is an easy workaround for this. If running QEMU directly, add the argument -machine pseries,cap-hpt-max-page-size=4096. If running QEMU via libvirt, add the following section to the guest's libvirt XML (via virsh edit [guest name] or the XML tab in virt-manager):

  <features>
    <hpt>
      <maxpagesize unit='KiB'>4</maxpagesize>
    </hpt>
  </features>