1<h2>memory_object_data_error</h2>
2<hr>
3<p>
4<strong>Function</strong> - An error prevents the supply of previously requested data.
5<h3>SYNOPSIS</h3>
6<pre>
7<strong>kern_return_t   memory_object_data_error</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>,
11                 <strong>kern_return_t</strong>                           <var>reason</var><strong>);</strong>
12</pre>
13<h3>PARAMETERS</h3>
14<dl>
15<p>
16<dt> <var>memory_control</var> 
17<dd>
18[in memory-cache-control send right]
19The memory cache control port 
20to be used by the memory manager for cache management requests. 
21This port is provided by the kernel in a <strong>memory_object_create</strong> call.
22<p>
23<dt> <var>offset</var> 
24<dd>
25[in scalar]
26The offset within the memory object, in bytes.
27<p>
28<dt> <var>size</var> 
29<dd>
30[in scalar]
31The number of bytes of data (starting at <var>offset</var>).  The number 
32must convert to an integral number of memory object pages.
33<p>
34<dt> <var>reason</var> 
35<dd>
36[in scalar]
37Reason for the error.
38</dl>
39<h3>DESCRIPTION</h3>
40<p>
41The <strong>memory_object_data_error</strong> function indicates that
42the memory manager 
43cannot provide the kernel with the data requested for the given region,
44specifying a reason for the error.
45<p>
46When the kernel issues a <strong>memory_object_data_request</strong> call, the memory
47manager can respond with a <strong>memory_object_data_error</strong>
48call to indicate that the 
49page cannot be retrieved, and that a memory failure exception should be raised 
50in any client threads that are waiting for the page.  Clients
51are permitted to catch 
52these exceptions and retry their page faults.  As a result, this
53call can be used to 
54report transient errors as well as permanent ones.  A memory manager can use 
55this call for both hardware errors (for example, disk failures) and software
56errors (for example, accessing data that does not exist or is protected).
57<h3>NOTES</h3>
58<p>
59If reason has a system code of <var>err_kern</var>, the kernel will substitute
60an error value 
61of <strong>KERN_MEMORY_ERROR</strong>.
62<h3>RETURN VALUES</h3>
63<p>
64Only generic errors apply.
65<h3>RELATED INFORMATION</h3>
66<p>
67Functions:
68<a href="memory_object_data_request.html"><strong>memory_object_data_request</strong></a>,
69<a href="memory_object_data_supply.html"><strong>memory_object_data_supply</strong></a>,
70<a href="MO_data_unavailable.html"><strong>memory_object_data_unavailable</strong></a>.
71