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

<h2>memory_object_data_unavailable</h2>\r<hr>\r<p>\r<strong>Function</strong> - Instruct kernel to zero-fill pages as requested data does not exist.\r<h3>SYNOPSIS</h3>\r<pre>\r<strong>kern_return_t   memory_object_data_unavailable</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><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_init</strong> or a \r<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</dl>\r<h3>DESCRIPTION</h3>\r<p>\rThe <strong>memory_object_data_unavailable</strong> function indicates\rthat the memory \rmanager cannot provide the kernel with the data requested for\rthe given region. \rInstead, the kernel should provide the data for this region.\r<p>\rA memory manager can use this call in any of the following situations:\r<ul>\r<li>\rWhen the object was created by the kernel \r(via <strong>memory_object_create</strong>) and \rthe kernel has not yet provided data for the region (via either\r<strong>memory_object_data_initialize</strong> or <strong>memory_object_data_return</strong>).\rIn this case, the\robject is a temporary memory object; the memory manager is the default \rmemory manager; and the kernel should provide zero-filled pages for the\robject.\r     <p>\r<li>\rWhen the object is a normal user-created memory object.  In this case, the \rkernel should provide zero-filled pages for the region.\r</ul>\r<h3>RETURN VALUES</h3>\r<p>\rOnly generic errors apply.\r<h3>RELATED INFORMATION</h3>\r<p>\rFunctions:\r<a href="memory_object_create.html"><strong>memory_object_create</strong></a>,\r<a href="memory_object_data_error.html"><strong>memory_object_data_error</strong></a>,\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