qemu/backends/dbus-vmstate1.xml

<?xml version="1.0" encoding="utf-8"?>
<node name="/" xmlns:doc="http://www.freedesktop.org/dbus/1.0/doc.dtd">
  <!--
      org.qemu.VMState1:

      This interface must be implemented at the object path
      ``/org/qemu/VMState1`` to support helper migration.
  -->
  <interface name="org.qemu.VMState1">

    <!--
        Id:

        A string that identifies the helper uniquely. (maximum 256 bytes
        including terminating NUL byte)

        .. note::

           The VMState helper ID namespace is its own namespace. In particular,
           it is not related to QEMU "id" used in -object/-device objects.
    -->
    <property name="Id" type="s" access="read"/>

    <!--
        Load:
        @data: data to restore the state.

        The method called on destination with the state to restore.

        The helper may be initially started in a waiting state (with an
        ``-incoming`` argument for example), and it may resume on success.

        An error may be returned to the caller.
    -->
    <method name="Load">
      <arg type="ay" name="data" direction="in"/>
    </method>

    <!--
        Save:
        @data: state data to save for later resume.

        The method called on the source to get the current state to be
        migrated. The helper should continue to run normally.

        An error may be returned to the caller.
    -->
    <method name="Save">
      <arg type="ay" name="data" direction="out"/>
    </method>
  </interface>
</node>