This is xnu-10002.1.13. See this file in:
<h2>thread_create</h2>
<hr>
<p>
<strong>Function</strong> - Create a thread within a task.
<h3>SYNOPSIS</h3>
<pre>
<strong>kern_return_t   thread_create</strong>
                <strong>(task_t</strong>                             <var>parent_task</var>,
                 <strong>thread_act_t</strong>                      <var>child_thread</var><strong>);</strong>
</pre>
<h3>PARAMETERS</h3>
<dl>
<p>
<dt> <var>parent_task</var> 
<dd>
[in task send right]
The port for the task that is to contain the new 
thread.
<p>
<dt> <var>child_thread</var> 
<dd>
[out thread send right]
The kernel-assigned name for the new thread.
</dl>
<h3>DESCRIPTION</h3>
<p>
The <strong>thread_create</strong> function creates a new thread within
<var>parent_task</var>.  The new thread has a suspend count of one and 
no processor state.
<p>
The new thread holds a send right for its thread kernel port.
A send right for the 
thread's kernel port is also returned to the calling task or
thread in <var>child_thread</var>. 
The new thread's exception ports are set to <strong>MACH_PORT_NULL</strong>.
<h3>NOTES</h3>
<p>
To get a new thread running, first use <strong>thread_set_state</strong>
to set a processor state 
for the thread.  Then, use <strong>thread_resume</strong> to schedule
the thread for execution. 
Alternately, use <strong>thread_create_running</strong>.
<h3>RETURN VALUES</h3>
<p>
Only generic errors apply.
<h3>RELATED INFORMATION</h3>
<p>
Functions:
<a href="task_create.html"><strong>task_create</strong></a>,
<a href="task_threads.html"><strong>task_threads</strong></a>,
<a href="thread_get_special_port.html"><strong>thread_get_special_port</strong></a>,
<a href="thread_get_state.html"><strong>thread_get_state</strong></a>,
<a href="thread_resume.html"><strong>thread_resume</strong></a>,
<a href="thread_set_special_port.html"><strong>thread_set_special_port</strong></a>,
<a href="thread_set_state.html"><strong>thread_set_state</strong></a>,
<a href="thread_suspend.html"><strong>thread_suspend</strong></a>,
<a href="thread_terminate.html"><strong>thread_terminate</strong></a>,
<a href="thread_create_running.html"><strong>thread_create_running</strong></a>.