xref: /xnu-11215/osfmk/man/memory_object_data_error.html (revision 186b8fce)

<h2>memory_object_data_error</h2>
<hr>
<p>
<strong>Function</strong> - An error prevents the supply of previously requested data.
<h3>SYNOPSIS</h3>
<pre>
<strong>kern_return_t   memory_object_data_error</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>kern_return_t</strong>                           <var>reason</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_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.
<p>
<dt> <var>reason</var>
<dd>
[in scalar]
Reason for the error.
</dl>
<h3>DESCRIPTION</h3>
<p>
The <strong>memory_object_data_error</strong> function indicates that
the memory manager
cannot provide the kernel with the data requested for the given region,
specifying a reason for the error.
<p>
When the kernel issues a <strong>memory_object_data_request</strong> call, the memory
manager can respond with a <strong>memory_object_data_error</strong>
call to indicate that the
page cannot be retrieved, and that a memory failure exception should be raised
in any client threads that are waiting for the page.  Clients
are permitted to catch
these exceptions and retry their page faults.  As a result, this
call can be used to
report transient errors as well as permanent ones.  A memory manager can use
this call for both hardware errors (for example, disk failures) and software
errors (for example, accessing data that does not exist or is protected).
<h3>NOTES</h3>
<p>
If reason has a system code of <var>err_kern</var>, the kernel will substitute
an error value
of <strong>KERN_MEMORY_ERROR</strong>.
<h3>RETURN VALUES</h3>
<p>
Only generic errors apply.
<h3>RELATED INFORMATION</h3>
<p>
Functions:
<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>,
<a href="MO_data_unavailable.html"><strong>memory_object_data_unavailable</strong></a>.