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mmap2 — map files or devices into memory
#include <sys/mman.h>
void
*mmap2( |
void *addr, |
| size_t length, | |
| int prot, | |
| int flags, | |
| int fd, | |
off_t pgoffset); |
This is probably not the system call that you are interested in; instead, see mmap(2), which describes the glibc wrapper 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).
On success, mmap2() returns
a pointer to the mapped area. On error −1 is returned
and errno is set
appropriately.
Problem with getting the data from user space.
(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).
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.
This page is part of release 3.54 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man−pages/.
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Copyright (C) 2002, Michael Kerrisk %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END Modified 31 Jan 2002, Michael Kerrisk <mtk.manpagesgmail.com> Added description of mmap2 Modified, 2004-11-25, mtk -- removed stray #endif in prototype |