---
name: "mmap2"
section: "2"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/mmap2"
---

# mmap2(2)

map files or devices into memory

## NAME

mmap2 - map files or devices into memory

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <sys/mman.h>    /* Definition of MAP_* and PROT_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
```

**void \*syscall(SYS\_mmap2, unsigned long** *addr***, unsigned long** *length***,**               **unsigned long** *prot***, unsigned long** *flags***,**               **unsigned long** *fd***, unsigned long** *pgoffset***);**

## DESCRIPTION

This is probably not the system call that you are interested in; instead, see [**mmap**(2)](/mmap/2.md), which describes the glibc wrapper function that invokes this system call.

The **mmap2**() system call provides the same interface as [**mmap**(2)](/mmap/2.md), except that the final argument specifies the offset into the file in 4096-byte units (instead of bytes, as is done by [**mmap**(2)](/mmap/2.md)). This enables applications that use a 32-bit *off\_t* to map large files (up to 2^44 bytes).

## RETURN VALUE

On success, **mmap2**() returns a pointer to the mapped area. On error, -1 is returned and *errno* is set to indicate the error.

## ERRORS

- **EFAULT**

  Problem with getting the data from user space.

- **EINVAL**

  (Various platforms where the page size is not 4096 bytes.) *offset \* 4096* is not a multiple of the system page size.

**mmap2**() can also return any of the errors described in [**mmap**(2)](/mmap/2.md).

## VERSIONS

On architectures where this system call is present, the glibc **mmap**() wrapper function invokes this system call rather than the [**mmap**(2)](/mmap/2.md) system call.

This system call does not exist on x86-64.

On ia64, the unit for *offset* is actually the system page size, rather than 4096 bytes.

## STANDARDS

Linux.

## HISTORY

Linux 2.3.31.

## SEE ALSO

[**getpagesize**(2)](/getpagesize/2.md), [**mmap**(2)](/mmap/2.md), [**mremap**(2)](/mremap/2.md), [**msync**(2)](/msync/2.md), [**shm\_open**(3)](/shm_open/3.md)