V4L2 munmap()
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## Name

v4l2-munmap — Unmap device memory

## Synopsis

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

`int munmap(` | void *start,
| size_t length`)`;

## Arguments

`start`

  Address of the mapped buffer as returned by the `mmap()` function.

`length`

  Length of the mapped buffer. This must be the same value as given to `mmap()` and returned by the driver in the struct v4l2_buffer `length` field for the single-planar API and in the struct v4l2_plane `length` field for the multi-planar API.

## Description

Unmaps a previously with the `mmap()` function mapped buffer and frees it, if possible.

## Return Value

On success `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.

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