osfmk/man/MO_data_unavailable.html

   1 <h2>memory_object_data_unavailable</h2>
   2 <hr>
   3 <p>
   4 <strong>Function</strong> - Instruct kernel to zero-fill pages as requested data does not exist.
   5 <h3>SYNOPSIS</h3>
   6 <pre>
   7 <strong>kern_return_t   memory_object_data_unavailable</strong>
   8                 <strong>(memory_object_control_t</strong>         <var>memory_control</var>,
   9                  <strong>vm_offset_t</strong>                             <var>offset</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>memory_control</var>
  16 <dd>
  17 [in memory-cache-control send right]
  18 The memory cache control port
  19 to be used by the memory manager for cache management requests.
  20 This port is provided by the kernel in a <strong>memory_object_init</strong> or a
  21 <strong>memory_object_create</strong> call.
  22 <p>
  23 <dt> <var>offset</var>
  24 <dd>
  25 [in scalar]
  26 The offset within the memory object, in bytes.
  27 <p>
  28 <dt> <var>size</var>
  29 <dd>
  30 [in scalar]
  31 The number of bytes of data (starting at <var>offset</var>).  The number
  32 must convert to an integral number of memory object pages.
  33 </dl>
  34 <h3>DESCRIPTION</h3>
  35 <p>
  36 The <strong>memory_object_data_unavailable</strong> function indicates
  37 that the memory
  38 manager cannot provide the kernel with the data requested for
  39 the given region.
  40 Instead, the kernel should provide the data for this region.
  41 <p>
  42 A memory manager can use this call in any of the following situations:
  43 <ul>
  44 <li>
  45 When the object was created by the kernel
  46 (via <strong>memory_object_create</strong>) and
  47 the kernel has not yet provided data for the region (via either
  48 <strong>memory_object_data_initialize</strong> or <strong>memory_object_data_return</strong>).
  49 In this case, the
  50 object is a temporary memory object; the memory manager is the default
  51 memory manager; and the kernel should provide zero-filled pages for the
  52 object.
  53      <p>
  54 <li>
  55 When the object is a normal user-created memory object.  In this case, the
  56 kernel should provide zero-filled pages for the region.
  57 </ul>
  58 <h3>RETURN VALUES</h3>
  59 <p>
  60 Only generic errors apply.
  61 <h3>RELATED INFORMATION</h3>
  62 <p>
  63 Functions:
  64 <a href="memory_object_create.html"><strong>memory_object_create</strong></a>,
  65 <a href="memory_object_data_error.html"><strong>memory_object_data_error</strong></a>,
  66 <a href="memory_object_data_request.html"><strong>memory_object_data_request</strong></a>,
  67 <a href="memory_object_data_supply.html"><strong>memory_object_data_supply</strong></a>.