osfmk/man/i386_set_ldt.html

   1 <h2>i386_set_ldt</h2>
<hr>
<p>
<strong>Function</strong> - Set per-thread segment descriptors.
<h3>SYNOPSIS</h3>
<pre>
<strong>kern_return_t   i386_set_ldt</strong>
                <strong>(thread_act_t</strong>                        <var>target_act</var>,
                 <strong>int</strong>                             <var>first_selector</var>,
                 <strong>descriptor_list_t</strong>                    <var>desc_list</var><strong>);</strong>
</pre>
<h3>PARAMETERS</h3>
<dl>
<p>
<dt> <var>target_act</var> 
<dd>
[in thread send right]
Thread whose segment descriptors are to be set.
<p>
<dt> <var>first_selector</var> 
<dd>
[in scalar]
Selector value (segment register value) corresponding to the 
first segment whose descriptor is to be set.
<p>
<dt> <var>desc_list</var> 
<dd>
[pointer to in array of <strong>descriptor_t</strong>]
Array of segment descriptors.  The 
following forms are permitted:
<ul>
<p>
<li>
Empty descriptor. The <strong>ACC_P</strong> flag (segment present) may or may 
not be set.
<p>
<li>
<strong>ACC_CALL_GATE</strong>--Converted into a system call gate.  The 
<strong>ACC_P</strong> flag must be set.
</ul>
<p>
All other descriptors must have both the <strong>ACC_P</strong> flag set and specify 
user mode access (<strong>ACC_PL_U</strong>).
<ul>
<p>
<li>
<strong>ACC_DATA</strong>.
<p>
<li>
<strong>ACC_DATA_W</strong>.
<p>
<li>
<strong>ACC_DATA_E</strong>.
<p>
<li>
<strong>ACC_DATA_EW</strong>.
<p>
<li>
<strong>ACC_CODE</strong>.
<p>
<li>
<strong>ACC_CODE_R</strong>.
<p>
<li>
<strong>ACC_CODE_C</strong>.
<p>
<li>
<strong>ACC_CODE_CR</strong>.
<p>
<li>
<strong>ACC_CALL_GATE_16</strong>.
<p>
<li>
<strong>ACC_CALL_GATE</strong>.
</ul>
</dl>
<h3>DESCRIPTION</h3>
<p>
The <strong>i386_set_ldt</strong> function allows a thread to have a
private local descriptor
table (LDT) which allows its local segments to map various ranges
of its address 
space.
<h3>RETURN VALUES</h3>
<p>
Only generic errors apply.
<h3>RELATED INFORMATION</h3>
<p>
Functions:
<a href="i386_get_ldt.html"><strong>i386_get_ldt<strong></a>.