LXR darwin-xnu/osfmk/man/vm

   1<h2>vm_inherit</h2>
   2<hr>
   3<p>
   4<strong>Function</strong> - Set a VM region's inheritance attribute.
   5<p>
   6<h3>SYNOPSIS</h3>
   7<pre>
   8<strong>kern_return_t   vm_inherit</strong>
   9                 <strong>(vm_task_t</strong>                   <var>target_task</var>,
  10                  <strong>vm_address_t</strong>                    <var>address</var>,
  11                  <strong>vm_size_t</strong>                          <var>size</var>,
  12                  <strong>vm_inherit_t</strong>            <var>new_inheritance</var><strong>);</strong>
  13</pre>
  14<h3>PARAMETERS</h3>
  15<dl>
  16<p>
  17<dt> <var>target_task</var> 
  18<dd>
  19[in task send right]
  20The port for the task whose address space contains 
  21the region.
  22<p>
  23<dt> <var>address</var> 
  24<dd>
  25[in scalar]
  26The starting address for the region.
  27<p>
  28<dt> <var>size</var> 
  29<dd>
  30[in scalar]
  31The number of bytes in the region.
  32<p>
  33<dt> <var>new_inheritance</var> 
  34<dd>
  35[in scalar]
  36The new inheritance attribute for the region.  Valid values are:
  37<dl>
  38<p>
  39<dt> <strong>VM_INHERIT_SHARE</strong>
  40<dd>
  41Allows child tasks to share the region.
  42<p>
  43<dt> <strong>VM_INHERIT_COPY</strong>
  44<dd>
  45Gives child tasks a copy of the region.
  46<p>
  47<dt> <strong>VM_INHERIT_NONE</strong>
  48<dd>
  49Provides no access to the region for child tasks.
  50</dl>
  51</dl>
  52<h3>DESCRIPTION</h3>
  53<p>
  54The <strong>vm_inherit</strong> function sets the inheritance attribute
  55for a region within the 
  56specified task's address space.  The inheritance attribute determines
  57the type of 
  58access established for child tasks at task creation.
  59<p>
  60Because inheritance applies to virtual pages, the specified <var>address</var>
  61and <var>size</var> are 
  62rounded to page boundaries, as follows: the region starts at
  63the beginning of the 
  64virtual page containing <var>address</var>; it ends at the end of the virtual
  65page containing 
  66<var>address</var> + <var>size</var> - 1.  
  67Because of this rounding to virtual page boundaries, the 
  68amount of memory affected may be greater than <var>size</var>.  Use 
  69<strong>host_page_size</strong> to find the current virtual page size.
  70<p>
  71A parent and a child task can share the same physical memory only if the
  72inheritance for the memory is set to <strong>VM_INHERIT_SHARE</strong> before
  73the child task is 
  74created.  Other than through the use of an external memory manager (see
  75<strong>vm_map</strong>), this is the only way that two tasks can share memory.
  76<p>
  77Note that all the threads within a task share the task's memory.
  78<h3>NOTES</h3>
  79<p>
  80This interface is machine word length specific because of the virtual address
  81parameter.
  82<h3>RETURN VALUES</h3>
  83<dl>
  84<p>
  85<dt> <strong>KERN_INVALID_ADDRESS</strong>
  86<dd>
  87The address is illegal or specifies a non-allocated region.
  88</dl>
  89<h3>RELATED INFORMATION</h3>
  90<p>
  91Functions:
  92<a href="task_create.html"><strong>task_create</strong></a>,
  93<a href="vm_map.html"><strong>vm_map</strong></a>,
  94<a href="vm_region.html"><strong>vm_region</strong></a>,
  95<a href="norma_task_clone.html"><strong>norma_task_create</strong></a>.
  96