1<h2>io_done_queue_wait</h2>
2<hr>
3<p>
4<strong>System Trap</strong> - Wait on an io_done_queue kernel object.
5<h3>SYNOPSIS</h3>
6<pre>
7<strong>kern_return_t	io_done_queue_wait</strong>
8		<strong>(mach_port_t</strong>             <var>queue</var>,
9		<strong>io_done_result_t</strong>       <var>*result</var><strong>);</strong>
10</pre>
11<h3>PARAMETERS</h3>
12<dl>
13<p>
14<dt> <var>queue</var>
15<dd>
16[in io-done-queue send right] The port referencing the io_done_queue 
17to be destroyed.
18<p>
19<dt> <var>result</var>
20<dd>
21[out structure] The data structure to be filled in with the completion
22status of the I/O operation.
23</dl>
24<h3>DESCRIPTION</h3>
25<p>
26The <strong>io_done_queue_wait</strong> interface is called to obtain the results of a
27previously requested asynchronous I/O operation. For each
28<strong>io_done_queue_wait</strong> invocation, the status of one I/O request is
29returned. If there are no pending I/O completions, io_done_queue_wait
30blocks in the kernel on the address of the completion queue. The
31mKernel, from interrupt context, enqueues (in FIFO order) completions
32(struct <strong>io_done_result</strong>'s) on the completion queue and posts a wakeup
33on the queue for each I/O completion. Completion processing previously
34done by the mKernel <strong>io_done thread</strong> is now done by the task thread when
35it awakens.
36<h3>RETURN VALUES</h3>
37<dl>
38  <dt> <strong>KERN_TERMINATED</strong>
39<dd>
40     Stale <strong>io_done_queue</strong> handle.
41     <p>
42
43  <dt> <strong>KERN_INVALID_ARGUMENT</strong>
44<dd>
45     Invalid <var>queue</var> parameter.
46     <p>
47<dt> <strong>KERN_INVALID_ARGUMENT</strong>
48<dd>
49     The <var>result</var> parameter is a bad address.
50     <p>
51</dl>
52<h3>RELATED INFORMATION</h3>
53<p>
54Functions:
55<a href="io_done_queue_create.html"><strong>io_done_queue_create</strong></a>,
56<a href="io_done_queue_wait.html"><strong>io_done_queue_wait</strong></a>,
57<a href="device_read_async.html"><strong>device_read_async</strong></a>,
58<a href="device_read_async_inband.html"><strong>device_read_async_inband</strong></a>,
59<a href="DR_overwrite_async.html"><strong>device_read_overwrite_async</strong></a>,
60<a href="device_write_async.html"><strong>device_write_async</strong></a>,
61<a href="device_write_async_inband.html"><strong>device_write_async_inband</strong></a>.
62