mirror of https://github.com/mkerrisk/man-pages
94 lines
2.9 KiB
Groff
94 lines
2.9 KiB
Groff
.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" Copyright (C) 2002, Michael Kerrisk
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Modified 31 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
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.\" Added description of mmap2
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.\" Modified, 2004-11-25, mtk -- removed stray #endif in prototype
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.\"
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.TH MMAP2 2 2008-04-22 "Linux" "Linux Programmer's Manual"
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.SH NAME
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mmap2 \- map files or devices into memory
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.SH SYNOPSIS
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.nf
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.B #include <sys/mman.h>
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.sp
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.BI "void *mmap2(void *" addr ", size_t " length ", int " prot ,
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.BI " int " flags ", int " fd ", off_t " pgoffset );
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.fi
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.SH DESCRIPTION
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The
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.BR mmap2 ()
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system call operates in exactly the same way as
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.BR mmap (2),
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except that the final argument specifies the offset into the
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file in 4096-byte units (instead of bytes, as is done by
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.BR mmap (2)).
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This enables applications that use a 32-bit
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.I off_t
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to map large files (up to 2^44 bytes).
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.SH "RETURN VALUE"
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On success,
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.BR mmap2 ()
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returns a pointer to the mapped area.
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On error \-1 is returned and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EFAULT
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Problem with getting the data from userspace.
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.TP
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.B EINVAL
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(Various platforms where the page size is not 4096 bytes.)
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.I offset * 4096
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is not a multiple of the system page size.
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.PP
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.BR mmap2 ()
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can return any of the same errors as
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.BR mmap (2).
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.SH VERSIONS
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.BR mmap2 ()
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is available since Linux 2.3.31.
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.SH "CONFORMING TO"
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This system call is Linux-specific.
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.SH NOTES
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Nowadays, the glibc
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.BR mmap ()
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wrapper function invokes this system call rather than the
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.BR mmap (2)
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system call.
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On ia64, the unit for
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.I offset
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is actually the system page size, rather than 4096 bytes.
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.\" ia64 can have page sizes ranging from 4kB to 64kB.
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.\" On cris, it looks like the unit might also be the page size,
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.\" which is 8192 bytes. -- mtk, June 2007
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.SH "SEE ALSO"
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.BR getpagesize (2),
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.BR mmap (2),
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.BR mremap (2),
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.BR msync (2),
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.BR shm_open (3)
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