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.\" Copyright (C) 2002, Michael Kerrisk
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.\" Modified 31 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
.\"	Added description of mmap2
.\" Modified, 2004-11-25, mtk -- removed stray #endif in prototype
.\"
.TH MMAP2 2 2008-04-22 "Linux" "Linux Programmer's Manual"
.SH NAME
mmap2 \- map files or devices into memory
.SH SYNOPSIS
.nf
.B #include <sys/mman.h>
.sp
.BI "void *mmap2(void *" addr ", size_t " length ", int " prot ,
.BI "             int " flags ", int " fd ", off_t " pgoffset );
.fi
.SH DESCRIPTION
The
.BR mmap2 ()
system call operates in exactly the same way as
.BR mmap (2),
except that the final argument specifies the offset into the
file in 4096-byte units (instead of bytes, as is done by
.BR mmap (2)).
This enables applications that use a 32-bit
.I off_t
to map large files (up to 2^44 bytes).
.SH "RETURN VALUE"
On success,
.BR mmap2 ()
returns a pointer to the mapped area.
On error \-1 is returned and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EFAULT
Problem with getting the data from userspace.
.TP
.B EINVAL
(Various platforms where the page size is not 4096 bytes.)
.I offset * 4096
is not a multiple of the system page size.
.PP
.BR mmap2 ()
can return any of the same errors as
.BR mmap (2).
.SH VERSIONS
.BR mmap2 ()
is available since Linux 2.3.31.
.SH "CONFORMING TO"
This system call is Linux-specific.
.SH NOTES
Nowadays, the glibc
.BR mmap ()
wrapper function invokes this system call rather than the
.BR mmap (2)
system call.

On ia64, the unit for
.I offset
is actually the system page size, rather than 4096 bytes.
.\" ia64 can have page sizes ranging from 4kB to 64kB.
.\" On cris, it looks like the unit might also be the page size,
.\" which is 8192 bytes. -- mtk, June 2007
.SH "SEE ALSO"
.BR getpagesize (2),
.BR mmap (2),
.BR mremap (2),
.BR msync (2),
.BR shm_open (3)
.SH COLOPHON
This page is part of release 3.22 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
