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

NAME

       remap_file_pages - create a nonlinear file mapping

SYNOPSIS

       #define _GNU_SOURCE
       #include <sys/mman.h>

       int remap_file_pages(void *addr, size_t size, int prot,
			    ssize_t pgoff, int flags);

DESCRIPTION

       The remap_file_pages() system call is used to create a nonlinear mapping, that is, a mapping in which the pages of the file are mapped into
       a nonsequential order in memory.  The advantage of using remap_file_pages() over using  repeated  calls	to  mmap(2)  is  that  the  former
       approach does not require the kernel to create additional VMA (Virtual Memory Area) data structures.

       To create a nonlinear mapping we perform the following steps:

       1. Use mmap(2) to create a mapping (which is initially linear).	This mapping must be created with the MAP_SHARED flag.

       2. Use  one or more calls to remap_file_pages() to rearrange the correspondence between the pages of the mapping and the pages of the file.
	  It is possible to map the same page of a file into multiple locations within the mapped region.

       The pgoff and size arguments specify the region of the file that is to be relocated within the mapping: pgoff is a file offset in units	of
       the system page size; size is the length of the region in bytes.

       The  addr  argument serves two purposes.  First, it identifies the mapping whose pages we want to rearrange.  Thus, addr must be an address
       that falls within a region previously mapped by a call to mmap(2).  Second, addr specifies the address at which the file  pages	identified
       by pgoff and size will be placed.

       The  values  specified  in  addr and size should be multiples of the system page size.  If they are not, then the kernel rounds both values
       down to the nearest multiple of the page size.

       The prot argument must be specified as 0.

       The flags argument has the same meaning as for mmap(2), but all flags other than MAP_NONBLOCK are ignored.

RETURN VALUE

       On success, remap_file_pages() returns 0.  On error, -1 is returned, and errno is set appropriately.

ERRORS

       EINVAL addr does not refer to a valid mapping created with the MAP_SHARED flag.

       EINVAL addr, size, prot, or pgoff is invalid.

VERSIONS

       The remap_file_pages() system call appeared in Linux 2.5.46; glibc support was added in version 2.3.3.

CONFORMING TO

       The remap_file_pages() system call is Linux-specific.

SEE ALSO

       getpagesize(2), mmap(2), mmap2(2), mprotect(2), mremap(2), msync(2), feature_test_macros(7)

COLOPHON

       This page is part of release 3.25 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/.

Linux								    2008-04-22						       REMAP_FILE_PAGES(2)