osfmk/man/vm_deallocate.html

   1 <h2>vm_deallocate</h2>
   2 <hr>
   3 <p>
   4 <strong>Function</strong> - Deallocate a region of virtual memory.
   5 <h3>SYNOPSIS</h3>
   6 <pre>
   7 <strong>kern_return_t   vm_deallocate</strong>
   8                 <strong>(vm_task_t</strong>                          <var>target_task</var>,
   9                  <strong>vm_address_t</strong>                           <var>address</var>,
  10                  <strong>vm_size_t</strong>                                 <var>size</var><strong>);</strong>
  11 </pre>
  12 <h3>PARAMETERS</h3>
  13 <dl>
  14 <p>
  15 <dt> <var>target_task</var>
  16 <dd>
  17 [in task send right]
  18 The port for the task in whose address space the
  19 region is to be deallocated.
  20 <p>
  21 <dt> <var>address</var>
  22 <dd>
  23 [in scalar]
  24 The starting address for the region.
  25 <p>
  26 <dt> <var>size</var>
  27 <dd>
  28 [in scalar]
  29 The number of bytes to deallocate.
  30 </dl>
  31 <h3>DESCRIPTION</h3>
  32 <p>
  33 The <strong>vm_deallocate</strong> function deallocates a region of
  34 virtual memory in the
  35 specified task's address space.
  36 The region starts at the beginning of the virtual page containing
  37 <var>address</var> and ends
  38 at the end of the virtual page containing <var>address</var>
  39 + <var>size</var> - 1.  Because of this
  40 rounding to virtual page boundaries, the amount of memory deallocated may be
  41 greater than <var>size</var>.  Use <strong>host_page_size</strong>
  42 to find the current virtual page size.
  43 <p>
  44 <strong>vm_deallocate</strong> affects only <var>target_task</var>.  Other tasks
  45 that have access to the deallocated memory can continue to reference it.
  46 <h3>NOTES</h3>
  47 <p>
  48 <strong>vm_deallocate</strong> can be used to deallocate memory passed
  49 as out-of-line data in a
  50 message.
  51 <p>
  52 This interface is machine word length specific because of the virtual address
  53 parameter.
  54 <h3>RETURN VALUES</h3>
  55 <dl>
  56 <p>
  57 <dt> <strong>KERN_INVALID_ADDRESS</strong>
  58 <dd>
  59 The address is illegal or specifies a non-allocated region.
  60 </dl>
  61 <h3>RELATED INFORMATION</h3>
  62 <p>
  63 Functions:
  64 <a href="mach_msg.html"><strong>mach_msg</strong></a>,
  65 <a href="vm_allocate.html"><strong>vm_allocate</strong></a>,
  66 <a href="vm_map.html"><strong>vm_map</strong></a>,
  67 <a href="host_page_size.html"><strong>host_page_size</strong></a>.