projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 13fec989 A |
1 | <h2>vm_deallocate</h2> |
| 2 | <hr> | |
| 3 | <p> | |
| 4 | <strong>Function</strong> - Deallocate a region of virtual memory. | |
| 5 | <h3>SYNOPSIS</h3> | |
| 6 | <pre> | |
| 7 | <strong>kern_return_t vm_deallocate</strong> | |
| 8 | <strong>(vm_task_t</strong> <var>target_task</var>, | |
| 9 | <strong>vm_address_t</strong> <var>address</var>, | |
| 10 | <strong>vm_size_t</strong> <var>size</var><strong>);</strong> | |
| 11 | </pre> | |
| 12 | <h3>PARAMETERS</h3> | |
| 13 | <dl> | |
| 14 | <p> | |
| 15 | <dt> <var>target_task</var> | |
| 16 | <dd> | |
| 17 | [in task send right] | |
| 18 | The port for the task in whose address space the | |
| 19 | region is to be deallocated. | |
| 20 | <p> | |
| 21 | <dt> <var>address</var> | |
| 22 | <dd> | |
| 23 | [in scalar] | |
| 24 | The starting address for the region. | |
| 25 | <p> | |
| 26 | <dt> <var>size</var> | |
| 27 | <dd> | |
| 28 | [in scalar] | |
| 29 | The number of bytes to deallocate. | |
| 30 | </dl> | |
| 31 | <h3>DESCRIPTION</h3> | |
| 32 | <p> | |
| 33 | The <strong>vm_deallocate</strong> function deallocates a region of | |
| 34 | virtual memory in the | |
| 35 | specified task's address space. | |
| 36 | The region starts at the beginning of the virtual page containing | |
| 37 | <var>address</var> and ends | |
| 38 | at the end of the virtual page containing <var>address</var> | |
| 39 | + <var>size</var> - 1. Because of this | |
| 40 | rounding to virtual page boundaries, the amount of memory deallocated may be | |
| 41 | greater than <var>size</var>. Use <strong>host_page_size</strong> | |
| 42 | to find the current virtual page size. | |
| 43 | <p> | |
| 44 | <strong>vm_deallocate</strong> affects only <var>target_task</var>. Other tasks | |
| 45 | that have access to the deallocated memory can continue to reference it. | |
| 46 | <h3>NOTES</h3> | |
| 47 | <p> | |
| 48 | <strong>vm_deallocate</strong> can be used to deallocate memory passed | |
| 49 | as out-of-line data in a | |
| 50 | message. | |
| 51 | <p> | |
| 52 | This interface is machine word length specific because of the virtual address | |
| 53 | parameter. | |
| 54 | <h3>RETURN VALUES</h3> | |
| 55 | <dl> | |
| 56 | <p> | |
| 57 | <dt> <strong>KERN_INVALID_ADDRESS</strong> | |
| 58 | <dd> | |
| 59 | The address is illegal or specifies a non-allocated region. | |
| 60 | </dl> | |
| 61 | <h3>RELATED INFORMATION</h3> | |
| 62 | <p> | |
| 63 | Functions: | |
| 64 | <a href="mach_msg.html"><strong>mach_msg</strong></a>, | |
| 65 | <a href="vm_allocate.html"><strong>vm_allocate</strong></a>, | |
| 66 | <a href="vm_map.html"><strong>vm_map</strong></a>, | |
| 67 | <a href="host_page_size.html"><strong>host_page_size</strong></a>. |