xref: /xnu-8020.140.41/osfmk/man/MO_data_unavailable.html (revision 27b03b360a988dfd3dfdf34262bb0042026747cc)
1*27b03b36SApple OSS Distributions<h2>memory_object_data_unavailable</h2>
2*27b03b36SApple OSS Distributions<hr>
3*27b03b36SApple OSS Distributions<p>
4*27b03b36SApple OSS Distributions<strong>Function</strong> - Instruct kernel to zero-fill pages as requested data does not exist.
5*27b03b36SApple OSS Distributions<h3>SYNOPSIS</h3>
6*27b03b36SApple OSS Distributions<pre>
7*27b03b36SApple OSS Distributions<strong>kern_return_t   memory_object_data_unavailable</strong>
8*27b03b36SApple OSS Distributions                <strong>(memory_object_control_t</strong>         <var>memory_control</var>,
9*27b03b36SApple OSS Distributions                 <strong>vm_offset_t</strong>                             <var>offset</var>,
10*27b03b36SApple OSS Distributions                 <strong>vm_size_t</strong>                                 <var>size</var><strong>);</strong>
11*27b03b36SApple OSS Distributions</pre>
12*27b03b36SApple OSS Distributions<h3>PARAMETERS</h3>
13*27b03b36SApple OSS Distributions<dl>
14*27b03b36SApple OSS Distributions<p>
15*27b03b36SApple OSS Distributions<dt> <var>memory_control</var>
16*27b03b36SApple OSS Distributions<dd>
17*27b03b36SApple OSS Distributions[in memory-cache-control send right]
18*27b03b36SApple OSS DistributionsThe memory cache control port
19*27b03b36SApple OSS Distributionsto be used by the memory manager for cache management requests.
20*27b03b36SApple OSS DistributionsThis port is provided by the kernel in a <strong>memory_object_init</strong> or a
21*27b03b36SApple OSS Distributions<strong>memory_object_create</strong> call.
22*27b03b36SApple OSS Distributions<p>
23*27b03b36SApple OSS Distributions<dt> <var>offset</var>
24*27b03b36SApple OSS Distributions<dd>
25*27b03b36SApple OSS Distributions[in scalar]
26*27b03b36SApple OSS DistributionsThe offset within the memory object, in bytes.
27*27b03b36SApple OSS Distributions<p>
28*27b03b36SApple OSS Distributions<dt> <var>size</var>
29*27b03b36SApple OSS Distributions<dd>
30*27b03b36SApple OSS Distributions[in scalar]
31*27b03b36SApple OSS DistributionsThe number of bytes of data (starting at <var>offset</var>).  The number
32*27b03b36SApple OSS Distributionsmust convert to an integral number of memory object pages.
33*27b03b36SApple OSS Distributions</dl>
34*27b03b36SApple OSS Distributions<h3>DESCRIPTION</h3>
35*27b03b36SApple OSS Distributions<p>
36*27b03b36SApple OSS DistributionsThe <strong>memory_object_data_unavailable</strong> function indicates
37*27b03b36SApple OSS Distributionsthat the memory
38*27b03b36SApple OSS Distributionsmanager cannot provide the kernel with the data requested for
39*27b03b36SApple OSS Distributionsthe given region.
40*27b03b36SApple OSS DistributionsInstead, the kernel should provide the data for this region.
41*27b03b36SApple OSS Distributions<p>
42*27b03b36SApple OSS DistributionsA memory manager can use this call in any of the following situations:
43*27b03b36SApple OSS Distributions<ul>
44*27b03b36SApple OSS Distributions<li>
45*27b03b36SApple OSS DistributionsWhen the object was created by the kernel
46*27b03b36SApple OSS Distributions(via <strong>memory_object_create</strong>) and
47*27b03b36SApple OSS Distributionsthe kernel has not yet provided data for the region (via either
48*27b03b36SApple OSS Distributions<strong>memory_object_data_initialize</strong> or <strong>memory_object_data_return</strong>).
49*27b03b36SApple OSS DistributionsIn this case, the
50*27b03b36SApple OSS Distributionsobject is a temporary memory object; the memory manager is the default
51*27b03b36SApple OSS Distributionsmemory manager; and the kernel should provide zero-filled pages for the
52*27b03b36SApple OSS Distributionsobject.
53*27b03b36SApple OSS Distributions     <p>
54*27b03b36SApple OSS Distributions<li>
55*27b03b36SApple OSS DistributionsWhen the object is a normal user-created memory object.  In this case, the
56*27b03b36SApple OSS Distributionskernel should provide zero-filled pages for the region.
57*27b03b36SApple OSS Distributions</ul>
58*27b03b36SApple OSS Distributions<h3>RETURN VALUES</h3>
59*27b03b36SApple OSS Distributions<p>
60*27b03b36SApple OSS DistributionsOnly generic errors apply.
61*27b03b36SApple OSS Distributions<h3>RELATED INFORMATION</h3>
62*27b03b36SApple OSS Distributions<p>
63*27b03b36SApple OSS DistributionsFunctions:
64*27b03b36SApple OSS Distributions<a href="memory_object_create.html"><strong>memory_object_create</strong></a>,
65*27b03b36SApple OSS Distributions<a href="memory_object_data_error.html"><strong>memory_object_data_error</strong></a>,
66*27b03b36SApple OSS Distributions<a href="memory_object_data_request.html"><strong>memory_object_data_request</strong></a>,
67*27b03b36SApple OSS Distributions<a href="memory_object_data_supply.html"><strong>memory_object_data_supply</strong></a>.
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