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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>V4L2 munmap()</TITLE
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>Video for Linux Two API Specification: Revision 0.24</TH
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><H1
><A
NAME="FUNC-MUNMAP"
></A
>V4L2 munmap()</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN14041"
></A
><H2
>Name</H2
>v4l2-munmap&nbsp;--&nbsp;Unmap device memory</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN14044"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><P
></P
><A
NAME="AEN14045"
></A
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include &lt;unistd.h&gt;
#include &lt;sys/mman.h&gt;</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int munmap</CODE
>(void *start, size_t length);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN14054"
></A
><H2
>Arguments</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><CODE
CLASS="PARAMETER"
>start</CODE
></DT
><DD
><P
>Address of the mapped buffer as returned by the
<A
HREF="r13889.htm"
><CODE
CLASS="FUNCTION"
>mmap()</CODE
></A
> function.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>length</CODE
></DT
><DD
><P
>Length of the mapped buffer. This must be the same
value as given to <CODE
CLASS="FUNCTION"
>mmap()</CODE
> and returned by the
driver in the struct&nbsp;<A
HREF="x5953.htm#V4L2-BUFFER"
>v4l2_buffer</A
> <CODE
CLASS="STRUCTFIELD"
>length</CODE
>
field.</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN14072"
></A
><H2
>Description</H2
><P
>Unmaps a previously with the <A
HREF="r13889.htm"
><CODE
CLASS="FUNCTION"
>mmap()</CODE
></A
> function mapped
buffer and frees it, if possible. </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN14077"
></A
><H2
>Return Value</H2
><P
>On success <CODE
CLASS="FUNCTION"
>munmap()</CODE
> returns 0, on
failure -1 and the <CODE
CLASS="VARNAME"
>errno</CODE
> variable is set
appropriately:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
></DT
><DD
><P
>The <CODE
CLASS="PARAMETER"
>start</CODE
> or
<CODE
CLASS="PARAMETER"
>length</CODE
> is incorrect, or no buffers have been
mapped yet.</P
></DD
></DL
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