gentoo-overlay/app-emulation/virtualbox/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <!-- maintainer-needed -->
  <use>
  <flag name="dtrace">Install dtrace Extension Pack</flag>
  <flag name="headless">Build without any graphic frontend</flag>
  <flag name="lvm">Build VBoxVolInfo that needs devicemapper from <pkg>sys-fs/lvm2</pkg>.</flag>
  <flag name="pax-kernel">Apply patch needed for pax enabled kernels.</flag>
  <flag name="sdk">Enable building of SDK</flag>
  <flag name="udev">Controls installation of special USB udev rules.</flag>
  <flag name="vboxwebsrv">Build and install the VirtualBox webservice</flag>
</use>
</pkgmetadata>