<h2>vm_inherit</h2> <hr> <p> <strong>Function</strong> - Set a VM region's inheritance attribute. <p> <h3>SYNOPSIS</h3> <pre> <strong>kern_return_t vm_inherit</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>vm_inherit_t</strong> <var>new_inheritance</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>new_inheritance</var> <dd> [in scalar] The new inheritance attribute for the region. Valid values are: <dl> <p> <dt> <strong>VM_INHERIT_SHARE</strong> <dd> Allows child tasks to share the region. <p> <dt> <strong>VM_INHERIT_COPY</strong> <dd> Gives child tasks a copy of the region. <p> <dt> <strong>VM_INHERIT_NONE</strong> <dd> Provides no access to the region for child tasks. </dl> </dl> <h3>DESCRIPTION</h3> <p> The <strong>vm_inherit</strong> function sets the inheritance attribute for a region within the specified task's address space. The inheritance attribute determines the type of access established for child tasks at task creation. <p> Because inheritance applies to virtual pages, the specified <var>address</var> and <var>size</var> are rounded to page boundaries, as follows: the region starts at the beginning of the virtual page containing <var>address</var>; it ends at the end of the virtual page containing <var>address</var> + <var>size</var> - 1. Because of this rounding to virtual page boundaries, the amount of memory affected may be greater than <var>size</var>. Use <strong>host_page_size</strong> to find the current virtual page size. <p> A parent and a child task can share the same physical memory only if the inheritance for the memory is set to <strong>VM_INHERIT_SHARE</strong> before the child task is created. Other than through the use of an external memory manager (see <strong>vm_map</strong>), this is the only way that two tasks can share memory. <p> Note that all the threads within a task share the task's memory. <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="task_create.html"><strong>task_create</strong></a>, <a href="vm_map.html"><strong>vm_map</strong></a>, <a href="vm_region.html"><strong>vm_region</strong></a>,