.. Permission is granted to copy, distribute and/or modify this
.. document under the terms of the GNU Free Documentation License,
.. Version 1.1 or any later version published by the Free Software
.. Foundation, with no Invariant Sections, no Front-Cover Texts
.. and no Back-Cover Texts. A copy of the license is included at
.. Documentation/userspace-api/media/fdl-appendix.rst.
..
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections

.. _dmx-munmap:

************
DVB munmap()
************

Name
====

dmx-munmap - Unmap device memory

.. warning:: This API is still experimental.


Synopsis
========

.. code-block:: c

    #include <unistd.h>
    #include <sys/mman.h>


.. c:function:: int munmap( void *start, size_t length )
    :name: dmx-munmap

Arguments
=========

``start``
    Address of the mapped buffer as returned by the
    :ref:`mmap() <dmx-mmap>` function.

``length``
    Length of the mapped buffer. This must be the same value as given to
    :ref:`mmap() <dmx-mmap>`.


Description
===========

Unmaps a previously with the :ref:`mmap() <dmx-mmap>` function mapped
buffer and frees it, if possible.


Return Value
============

On success :ref:`munmap() <dmx-munmap>` returns 0, on failure -1 and the
``errno`` variable is set appropriately:

EINVAL
    The ``start`` or ``length`` is incorrect, or no buffers have been
    mapped yet.