+++ /dev/null
-.\" Copyright (c) 1996 Tom Bjorkholm <tomb@mydata.se>
-.\"
-.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
-.\" This is free documentation; you can redistribute it and/or
-.\" modify it under the terms of the GNU General Public License as
-.\" published by the Free Software Foundation; either version 2 of
-.\" the License, or (at your option) any later version.
-.\"
-.\" The GNU General Public License's references to "object code"
-.\" and "executables" are to be interpreted as the output of any
-.\" document formatting or typesetting system, including
-.\" intermediate and printed output.
-.\"
-.\" This manual is distributed in the hope that it will be useful,
-.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
-.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-.\" GNU General Public License for more details.
-.\"
-.\" You should have received a copy of the GNU General Public
-.\" License along with this manual; if not, see
-.\" <http://www.gnu.org/licenses/>.
-.\" %%%LICENSE_END
-.\"
-.\" 1996-04-11 Tom Bjorkholm <tomb@mydata.se>
-.\" First version written (1.3.86)
-.\" 1996-04-12 Tom Bjorkholm <tomb@mydata.se>
-.\" Update for Linux 1.3.87 and later
-.\" 2005-10-11 mtk: Added NOTES for MREMAP_FIXED; revised EINVAL text.
-.\"
-.TH MREMAP 2 2010-06-10 "Linux" "Linux Programmer's Manual"
-.SH NAME
-mremap \- remap a virtual memory address
-.SH SYNOPSIS
-.nf
-.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
-.br
-.B #include <sys/mman.h>
-.sp
-.BI "void *mremap(void *" old_address ", size_t " old_size ,
-.BI " size_t " new_size ", int " flags ", ... /* void *" new_address " */);"
-.fi
-.SH DESCRIPTION
-.BR mremap ()
-expands (or shrinks) an existing memory mapping, potentially
-moving it at the same time (controlled by the \fIflags\fP argument and
-the available virtual address space).
-
-\fIold_address\fP is the old address of the virtual memory block that you
-want to expand (or shrink).
-Note that \fIold_address\fP has to be page
-aligned.
-\fIold_size\fP is the old size of the
-virtual memory block.
-\fInew_size\fP is the requested size of the
-virtual memory block after the resize.
-An optional fifth argument,
-.IR new_address ,
-may be provided; see the description of
-.B MREMAP_FIXED
-below.
-
-In Linux the memory is divided into pages.
-A user process has (one or)
-several linear virtual memory segments.
-Each virtual memory segment has one
-or more mappings to real memory pages (in the page table).
-Each virtual memory segment has its own
-protection (access rights), which may cause
-a segmentation violation if the memory is accessed incorrectly (e.g.,
-writing to a read-only segment).
-Accessing virtual memory outside of the
-segments will also cause a segmentation violation.
-
-.BR mremap ()
-uses the Linux page table scheme.
-.BR mremap ()
-changes the
-mapping between virtual addresses and memory pages.
-This can be used to implement a very efficient
-.BR realloc (3).
-
-The \fIflags\fP bit-mask argument may be 0, or include the following flag:
-.TP
-.B MREMAP_MAYMOVE
-By default, if there is not sufficient space to expand a mapping
-at its current location, then
-.BR mremap ()
-fails.
-If this flag is specified, then the kernel is permitted to
-relocate the mapping to a new virtual address, if necessary.
-If the mapping is relocated,
-then absolute pointers into the old mapping location
-become invalid (offsets relative to the starting address of
-the mapping should be employed).
-.TP
-.BR MREMAP_FIXED " (since Linux 2.3.31)"
-This flag serves a similar purpose to the
-.B MAP_FIXED
-flag of
-.BR mmap (2).
-If this flag is specified, then
-.BR mremap ()
-accepts a fifth argument,
-.IR "void\ *new_address" ,
-which specifies a page-aligned address to which the mapping must
-be moved.
-Any previous mapping at the address range specified by
-.I new_address
-and
-.I new_size
-is unmapped.
-If
-.B MREMAP_FIXED
-is specified, then
-.B MREMAP_MAYMOVE
-must also be specified.
-.PP
-If the memory segment specified by
-.I old_address
-and
-.I old_size
-is locked (using
-.BR mlock (2)
-or similar), then this lock is maintained when the segment is
-resized and/or relocated.
-As a consequence, the amount of memory locked by the process may change.
-.SH RETURN VALUE
-On success
-.BR mremap ()
-returns a pointer to the new virtual memory area.
-On error, the value
-.B MAP_FAILED
-(that is, \fI(void\ *)\ \-1\fP) is returned,
-and \fIerrno\fP is set appropriately.
-.SH ERRORS
-.TP
-.B EAGAIN
-The caller tried to expand a memory segment that is locked,
-but this was not possible without exceeding the
-.B RLIMIT_MEMLOCK
-resource limit.
-.TP
-.B EFAULT
-"Segmentation fault." Some address in the range
-\fIold_address\fP to \fIold_address\fP+\fIold_size\fP is an invalid
-virtual memory address for this process.
-You can also get
-.B EFAULT
-even if there exist mappings that cover the
-whole address space requested, but those mappings are of different types.
-.TP
-.B EINVAL
-An invalid argument was given.
-Possible causes are: \fIold_address\fP was not
-page aligned; a value other than
-.B MREMAP_MAYMOVE
-or
-.B MREMAP_FIXED
-was specified in
-.IR flags ;
-.I new_size
-was zero;
-.I new_size
-or
-.I new_address
-was invalid;
-or the new address range specified by
-.I new_address
-and
-.I new_size
-overlapped the old address range specified by
-.I old_address
-and
-.IR old_size ;
-or
-.B MREMAP_FIXED
-was specified without also specifying
-.BR MREMAP_MAYMOVE .
-.TP
-.B ENOMEM
-The memory area cannot be expanded at the current virtual address, and the
-.B MREMAP_MAYMOVE
-flag is not set in \fIflags\fP.
-Or, there is not enough (virtual) memory available.
-.SH CONFORMING TO
-This call is Linux-specific, and should not be used in programs
-intended to be portable.
-.\" 4.2BSD had a (never actually implemented)
-.\" .BR mremap (2)
-.\" call with completely different semantics.
-.SH NOTES
-Prior to version 2.4, glibc did not expose the definition of
-.BR MREMAP_FIXED ,
-and the prototype for
-.BR mremap ()
-did not allow for the
-.I new_address
-argument.
-.SH SEE ALSO
-.BR brk (2),
-.BR getpagesize (2),
-.BR getrlimit (2),
-.BR mlock (2),
-.BR mmap (2),
-.BR sbrk (2),
-.BR malloc (3),
-.BR realloc (3)
-
-Your favorite text book on operating systems
-for more information on paged memory
-(e.g., \fIModern Operating Systems\fP by Andrew S. Tanenbaum,
-\fIInside Linux\fP by Randolf Bentson,
-\fIThe Design of the UNIX Operating System\fP by Maurice J. Bach)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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