'Warn about untested driver configurations.
This will log a warning message about untested driver or host arch
configurations to indicate to administrators that the quality is
unknown. Currently, only qemu or kvm on intel 32- or 64-bit systems
is tested upstream.'

def _do_quality_warnings(self):

    caps = self._host.get_capabilities()
    hostarch = caps.host.cpu.arch
    if ((CONF.libvirt.virt_type not in ('qemu', 'kvm')) or (hostarch not in (fields.Architecture.I686, fields.Architecture.X86_64))):
        LOG.warning('The    libvirt    driver    is    not    tested    on    %(type)s/%(arch)s    by    the    OpenStack    project    and    thus    its    quality    can    not    be    ensured.    For    more    information,    see:    http://docs.openstack.org/developer/nova/support-matrix.html', {'type': CONF.libvirt.virt_type, 'arch': hostarch})
