[apple/xnu.git] / osfmk / man / memory_object_data_error.html

<h2>memory_object_data_error</h2>\r<hr>\r<p>\r<strong>Function</strong> - An error prevents the supply of previously requested data.\r<h3>SYNOPSIS</h3>\r<pre>\r<strong>kern_return_t   memory_object_data_error</strong>\r                <strong>(memory_object_control_t</strong>         <var>memory_control</var>,\r                 <strong>vm_offset_t</strong>                             <var>offset</var>,\r                 <strong>vm_size_t</strong>                                 <var>size</var>,\r                 <strong>kern_return_t</strong>                           <var>reason</var><strong>);</strong>\r</pre>\r<h3>PARAMETERS</h3>\r<dl>\r<p>\r<dt> <var>memory_control</var> \r<dd>\r[in memory-cache-control send right]\rThe memory cache control port \rto be used by the memory manager for cache management requests. \rThis port is provided by the kernel in a <strong>memory_object_create</strong> call.\r<p>\r<dt> <var>offset</var> \r<dd>\r[in scalar]\rThe offset within the memory object, in bytes.\r<p>\r<dt> <var>size</var> \r<dd>\r[in scalar]\rThe number of bytes of data (starting at <var>offset</var>).  The number \rmust convert to an integral number of memory object pages.\r<p>\r<dt> <var>reason</var> \r<dd>\r[in scalar]\rReason for the error.\r</dl>\r<h3>DESCRIPTION</h3>\r<p>\rThe <strong>memory_object_data_error</strong> function indicates that\rthe memory manager \rcannot provide the kernel with the data requested for the given region,\rspecifying a reason for the error.\r<p>\rWhen the kernel issues a <strong>memory_object_data_request</strong> call, the memory\rmanager can respond with a <strong>memory_object_data_error</strong>\rcall to indicate that the \rpage cannot be retrieved, and that a memory failure exception should be raised \rin any client threads that are waiting for the page.  Clients\rare permitted to catch \rthese exceptions and retry their page faults.  As a result, this\rcall can be used to \rreport transient errors as well as permanent ones.  A memory manager can use \rthis call for both hardware errors (for example, disk failures) and software\rerrors (for example, accessing data that does not exist or is protected).\r<h3>NOTES</h3>\r<p>\rIf reason has a system code of <var>err_kern</var>, the kernel will substitute\ran error value \rof <strong>KERN_MEMORY_ERROR</strong>.\r<h3>RETURN VALUES</h3>\r<p>\rOnly generic errors apply.\r<h3>RELATED INFORMATION</h3>\r<p>\rFunctions:\r<a href="memory_object_data_request.html"><strong>memory_object_data_request</strong></a>,\r<a href="memory_object_data_supply.html"><strong>memory_object_data_supply</strong></a>,\r<a href="MO_data_unavailable.html"><strong>memory_object_data_unavailable</strong></a>.\r