<h2>io_done_queue_wait</h2>

<strong>System Trap</strong> - Wait on an io_done_queue kernel object.

<h3>SYNOPSIS</h3>

<strong>kern_return_t io_done_queue_wait</strong>

<strong>(mach_port_t</strong> <var>queue</var>,

<strong>io_done_result_t</strong> <var>*result</var><strong>);</strong>

<h3>PARAMETERS</h3>

<dt> <var>queue</var>

[in io-done-queue send right] The port referencing the io_done_queue

to be destroyed.

<dt> <var>result</var>

[out structure] The data structure to be filled in with the completion

status of the I/O operation.

<h3>DESCRIPTION</h3>

The <strong>io_done_queue_wait</strong> interface is called to obtain the results of a

previously requested asynchronous I/O operation. For each

<strong>io_done_queue_wait</strong> invocation, the status of one I/O request is

returned. If there are no pending I/O completions, io_done_queue_wait

blocks in the kernel on the address of the completion queue. The

mKernel, from interrupt context, enqueues (in FIFO order) completions

(struct <strong>io_done_result</strong>'s) on the completion queue and posts a wakeup

on the queue for each I/O completion. Completion processing previously

done by the mKernel <strong>io_done thread</strong> is now done by the task thread when

it awakens.

<h3>RETURN VALUES</h3>

<dt> <strong>KERN_TERMINATED</strong>

Stale <strong>io_done_queue</strong> handle.

<p>

<dt> <strong>KERN_INVALID_ARGUMENT</strong>

Invalid <var>queue</var> parameter.

<p>

<dt> <strong>KERN_INVALID_ARGUMENT</strong>

The <var>result</var> parameter is a bad address.

<p>

<h3>RELATED INFORMATION</h3>

Functions:

<a href="io_done_queue_create.html"><strong>io_done_queue_create</strong></a>,

<a href="io_done_queue_wait.html"><strong>io_done_queue_wait</strong></a>,

<a href="device_read_async.html"><strong>device_read_async</strong></a>,

<a href="device_read_async_inband.html"><strong>device_read_async_inband</strong></a>,

<a href="DR_overwrite_async.html"><strong>device_read_overwrite_async</strong></a>,

<a href="device_write_async.html"><strong>device_write_async</strong></a>,

<a href="device_write_async_inband.html"><strong>device_write_async_inband</strong></a>.