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CentOS 7.0 - man page for mmap2 (centos section 2)

MMAP2(2)				      Linux Programmer's Manual 				     MMAP2(2)

NAME
mmap2 - map files or devices into memory
SYNOPSIS
#include <sys/mman.h> void *mmap2(void *addr, size_t length, int prot, int flags, int fd, off_t pgoffset);
DESCRIPTION
This is probably not the system call you are interested; instead, see mmap(2), which describes the glibc wrap- per function that invokes this system call. The mmap2() system call provides the same interface as mmap(2), except that the final argument specifies the offset into the file in 4096-byte units (instead of bytes, as is done by mmap(2)). 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 appropri- ately.
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 sys- tem page size. mmap2() can also return any of the errors described in mmap(2).
VERSIONS
mmap2() is available since Linux 2.3.31.
CONFORMING TO
This system call is Linux-specific.
NOTES
Nowadays, the glibc mmap() wrapper function invokes this system call rather than the mmap(2) system call. On ia64, the unit for offset is actually the system page size, rather than 4096 bytes.
SEE ALSO
getpagesize(2), mmap(2), mremap(2), msync(2), shm_open(3)
COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and informa- tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2012-04-16 MMAP2(2)


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