man2/mmap2.2

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  25 .\" Modified 31 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
  26 .\"     Added description of mmap2
  27 .\" Modified, 2004-11-25, mtk -- removed stray #endif in prototype
  28 .\"
  29 .TH MMAP2 2 2012-04-16 "Linux" "Linux Programmer's Manual"
  30 .SH NAME
  31 mmap2 \- map files or devices into memory
  32 .SH SYNOPSIS
  33 .nf
  34 .B #include <sys/mman.h>
  35 .sp
  36 .BI "void *mmap2(void *" addr ", size_t " length ", int " prot ,
  37 .BI "             int " flags ", int " fd ", off_t " pgoffset );
  38 .fi
  39 .SH DESCRIPTION
  40 This is probably not the system call you are interested; instead, see
  41 .BR mmap (2),
  42 which describes the glibc wrapper function that invokes this system call.
  43
  44 The
  45 .BR mmap2 ()
  46 system call provides the same interface as
  47 .BR mmap (2),
  48 except that the final argument specifies the offset into the
  49 file in 4096-byte units (instead of bytes, as is done by
  50 .BR mmap (2)).
  51 This enables applications that use a 32-bit
  52 .I off_t
  53 to map large files (up to 2^44 bytes).
  54 .SH RETURN VALUE
  55 On success,
  56 .BR mmap2 ()
  57 returns a pointer to the mapped area.
  58 On error \-1 is returned and
  59 .I errno
  60 is set appropriately.
  61 .SH ERRORS
  62 .TP
  63 .B EFAULT
  64 Problem with getting the data from user space.
  65 .TP
  66 .B EINVAL
  67 (Various platforms where the page size is not 4096 bytes.)
  68 .I offset * 4096
  69 is not a multiple of the system page size.
  70 .PP
  71 .BR mmap2 ()
  72 can also return any of the errors described in
  73 .BR mmap (2).
  74 .SH VERSIONS
  75 .BR mmap2 ()
  76 is available since Linux 2.3.31.
  77 .SH CONFORMING TO
  78 This system call is Linux-specific.
  79 .SH NOTES
  80 Nowadays, the glibc
  81 .BR mmap ()
  82 wrapper function invokes this system call rather than the
  83 .BR mmap (2)
  84 system call.
  85
  86 On ia64, the unit for
  87 .I offset
  88 is actually the system page size, rather than 4096 bytes.
  89 .\" ia64 can have page sizes ranging from 4kB to 64kB.
  90 .\" On cris, it looks like the unit might also be the page size,
  91 .\" which is 8192 bytes. -- mtk, June 2007
  92 .SH SEE ALSO
  93 .BR getpagesize (2),
  94 .BR mmap (2),
  95 .BR mremap (2),
  96 .BR msync (2),
  97 .BR shm_open (3)