Hi Peter,

+ - The optional ``iothreads`` sub-element allows specifying multiple IOThreads + via the ``iothread`` sub-element with attribute ``id`` the disk will use + for I/O operations. Optionally the ``iothread`` element can have multiple + ``queue`` subelements specifying that given iothread should be used to + handle given queues. :since:`Since XXXXXX`.

Although this says that the ``queue`` sub-elements are optional, it may be clearer to add another sentence that explains the device will automatically assign virtqueues to the given ``iothread`` sub-elements when ``queue`` is not given. That answers the question of "what is the behavior of omitting ``queue``?".

+ <driver name='qemu' queues='2'> + <iothreads> + <iothread id='1'> + <queue id='1'/> + </iothread> + <iothread id='2'> + <queue id='1'/> + </iothread>

Each queue can only be assigned to 1 IOThread, so <queue id='1'/> cannot be assigned to multiple IOThreads. Thank you, Stefan