# File lib/vagrant-libvirt/config.rb, line 427
      def pci(options = {})
        if options[:bus].nil? || options[:slot].nil? || options[:function].nil?
          raise 'Bus AND slot AND function must be specified. Check `lspci` for that numbers.'
        end

        @pcis = [] if @pcis == UNSET_VALUE

        @pcis.push(bus:       options[:bus],
                   slot:      options[:slot],
                   function:  options[:function])
      end