xnu-2422.1.72.tar.gz

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

<h2>vm_msync</h2>
<hr>
<p>
<strong>Function</strong> - Synchronize the specified region of virtual memory.
<h3>SYNOPSIS</h3>
<pre>
<strong>kern_return_t   vm_msync</strong>
                <strong>(vm_task_t</strong>                          <var>target_task</var>,
                 <strong>vm_address_t</strong>                           <var>address</var>,
                 <strong>vm_size_t</strong>                                 <var>size</var>,
                 <strong>target_task</strong>                         <var>sync_flags</var><strong>);</strong>
</pre>
<h3>PARAMETERS</h3>
<dl>
<p>
<dt> <var>target_task</var> 
<dd>
[in task send right]
The port for the task whose address space contains 
the region.
<p>
<dt> <var>address</var> 
<dd>
[in scalar]
The starting address for the region.
<p>
<dt> <var>size</var> 
<dd>
[in scalar]
The number of bytes in the region.
<p>
<dt> <var>sync_flags</var> 
<dd>
[in scalar]
The bit-wise <strong>OR</strong> of flags affecting the synchronization. 	
Specifying both <strong>VM_SYNC_SYNCHRONOUS</strong> and
<strong>VM_SYNC_ASYNCHRONOUS</strong> is invalid.
<dl>
<p>
<dt> <strong>VM_SYNC_INVALIDATE</strong>
<dd>
Flushes pages in the range.  Only precious pages are returned to 
the memory manager unless either <strong>VM_SYNC_SYNCHRONOUS</strong> or
<strong>VM_SYNC_ASYNCHRONOUS</strong> is also set.
<p>
<dt> <strong>VM_SYNC_SYNCHRONOUS</strong>
<dd>
Writes dirty and precious pages back to the memory manager, 
waits for pages to reach backing storage.
<p>
<dt> <strong>VM_SYNC_ASYNCHRONOUS</strong>
<dd>
Writes dirty and precious pages back to the memory manager, 
returns without waiting for pages to reach backing storage.
</dl>
</dl>
<h3>DESCRIPTION</h3>
<p>
The <strong>vm_msync</strong> function synchronizes the contents of
a memory range with its 
backing store image by flushing or cleaning the contents of the
specified range 
to the range's memory manager, engaging in a synchronization protocol with 
the manager (<strong>memory_object_synchronize</strong>).  
The client does not return from 
this call until the memory manager responds (to the kernel) with
<strong>memory_object_synchronize_completed</strong>.
<h3>NOTES</h3>
<p>
This interface is machine word length specific because of the virtual address
parameter.
<h3>RETURN VALUES</h3>
<dl>
<p>
<dt> <strong>KERN_INVALID_ADDRESS</strong>
<dd>
The address is illegal or specifies a non-allocated region.
</dl>
<h3>RELATED INFORMATION</h3>
<p>
Functions:
<a href="memory_object_synchronize.html"><strong>memory_object_synchronize</strong></a>,
<a href="MO_SY_completed.html"><strong>memory_object_synchronize_completed</strong></a>.