osfmk/man/i386_set_ldt.html

   1 <h2>i386_set_ldt</h2>
   2 <hr>
   3 <p>
   4 <strong>Function</strong> - Set per-thread segment descriptors.
   5 <h3>SYNOPSIS</h3>
   6 <pre>
   7 <strong>kern_return_t   i386_set_ldt</strong>
   8                 <strong>(thread_act_t</strong>                        <var>target_act</var>,
   9                  <strong>int</strong>                             <var>first_selector</var>,
  10                  <strong>descriptor_list_t</strong>                    <var>desc_list</var><strong>);</strong>
  11 </pre>
  12 <h3>PARAMETERS</h3>
  13 <dl>
  14 <p>
  15 <dt> <var>target_act</var>
  16 <dd>
  17 [in thread send right]
  18 Thread whose segment descriptors are to be set.
  19 <p>
  20 <dt> <var>first_selector</var>
  21 <dd>
  22 [in scalar]
  23 Selector value (segment register value) corresponding to the
  24 first segment whose descriptor is to be set.
  25 <p>
  26 <dt> <var>desc_list</var>
  27 <dd>
  28 [pointer to in array of <strong>descriptor_t</strong>]
  29 Array of segment descriptors.  The
  30 following forms are permitted:
  31 <ul>
  32 <p>
  33 <li>
  34 Empty descriptor. The <strong>ACC_P</strong> flag (segment present) may or may
  35 not be set.
  36 <p>
  37 <li>
  38 <strong>ACC_CALL_GATE</strong>--Converted into a system call gate.  The
  39 <strong>ACC_P</strong> flag must be set.
  40 </ul>
  41 <p>
  42 All other descriptors must have both the <strong>ACC_P</strong> flag set and specify
  43 user mode access (<strong>ACC_PL_U</strong>).
  44 <ul>
  45 <p>
  46 <li>
  47 <strong>ACC_DATA</strong>.
  48 <p>
  49 <li>
  50 <strong>ACC_DATA_W</strong>.
  51 <p>
  52 <li>
  53 <strong>ACC_DATA_E</strong>.
  54 <p>
  55 <li>
  56 <strong>ACC_DATA_EW</strong>.
  57 <p>
  58 <li>
  59 <strong>ACC_CODE</strong>.
  60 <p>
  61 <li>
  62 <strong>ACC_CODE_R</strong>.
  63 <p>
  64 <li>
  65 <strong>ACC_CODE_C</strong>.
  66 <p>
  67 <li>
  68 <strong>ACC_CODE_CR</strong>.
  69 <p>
  70 <li>
  71 <strong>ACC_CALL_GATE_16</strong>.
  72 <p>
  73 <li>
  74 <strong>ACC_CALL_GATE</strong>.
  75 </ul>
  76 </dl>
  77 <h3>DESCRIPTION</h3>
  78 <p>
  79 The <strong>i386_set_ldt</strong> function allows a thread to have a
  80 private local descriptor
  81 table (LDT) which allows its local segments to map various ranges
  82 of its address
  83 space.
  84 <h3>RETURN VALUES</h3>
  85 <p>
  86 Only generic errors apply.
  87 <h3>RELATED INFORMATION</h3>
  88 <p>
  89 Functions:
  90 <a href="i386_get_ldt.html"><strong>i386_get_ldt<strong></a>.