osfmk/man/MO_data_unavailable.html

   1 <h2>memory_object_data_unavailable</h2>
<hr>
<p>
<strong>Function</strong> - Instruct kernel to zero-fill pages as requested data does not exist.
<h3>SYNOPSIS</h3>
<pre>
<strong>kern_return_t   memory_object_data_unavailable</strong>
                <strong>(memory_object_control_t</strong>         <var>memory_control</var>,
                 <strong>vm_offset_t</strong>                             <var>offset</var>,
                 <strong>vm_size_t</strong>                                 <var>size</var><strong>);</strong>
</pre>
<h3>PARAMETERS</h3>
<dl>
<p>
<dt> <var>memory_control</var> 
<dd>
[in memory-cache-control send right]
The memory cache control port 
to be used by the memory manager for cache management requests. 
This port is provided by the kernel in a <strong>memory_object_init</strong> or a 
<strong>memory_object_create</strong> call.
<p>
<dt> <var>offset</var> 
<dd>
[in scalar]
The offset within the memory object, in bytes.
<p>
<dt> <var>size</var> 
<dd>
[in scalar]
The number of bytes of data (starting at <var>offset</var>).  The number 
must convert to an integral number of memory object pages.
</dl>
<h3>DESCRIPTION</h3>
<p>
The <strong>memory_object_data_unavailable</strong> function indicates
that the memory 
manager cannot provide the kernel with the data requested for
the given region. 
Instead, the kernel should provide the data for this region.
<p>
A memory manager can use this call in any of the following situations:
<ul>
<li>
When the object was created by the kernel 
(via <strong>memory_object_create</strong>) and 
the kernel has not yet provided data for the region (via either
<strong>memory_object_data_initialize</strong> or <strong>memory_object_data_return</strong>).
In this case, the
object is a temporary memory object; the memory manager is the default 
memory manager; and the kernel should provide zero-filled pages for the
object.
     <p>
<li>
When the object is a normal user-created memory object.  In this case, the 
kernel should provide zero-filled pages for the region.
</ul>
<h3>RETURN VALUES</h3>
<p>
Only generic errors apply.
<h3>RELATED INFORMATION</h3>
<p>
Functions:
<a href="memory_object_create.html"><strong>memory_object_create</strong></a>,
<a href="memory_object_data_error.html"><strong>memory_object_data_error</strong></a>,
<a href="memory_object_data_request.html"><strong>memory_object_data_request</strong></a>,
<a href="memory_object_data_supply.html"><strong>memory_object_data_supply</strong></a>.