gentoo-overlay/app-emulation/virt-manager/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <herd>virtualization</herd>
  <use>
    <flag name='policykit'>
      Enables <pkg>sys-auth/polkit</pkg> authentication support,
      required when using <pkg>app-emulation/libvirt</pkg> with
      PolicyKit authentication
    </flag>
    <flag name='sasl'>
      Depend on the proper libraries needed to connect to SASL-enabled
      libvirtd instances (e.g. Kerberos-protected instances).
    </flag>
	<flag name='spice'>
		Support connecting to SPICE-enabled virtual machines.
	</flag>
	<flag name='vnc'>
		Support connecting to VNC-enabled virtual machines.
	</flag>
  </use>
</pkgmetadata>