Originální popis anglicky:
remap_file_pages - create a non-linear file mapping
Návod, kniha: Linux Programmer's Manual
#include <sys/mman.h>
int remap_file_pages(void *start, size_t
size, int prot, ssize_t
pgoff, int flags);
The
remap_file_pages() system call is used to create a non-linear
mapping, that is, a mapping in which the pages of the file are mapped into a
non-sequential 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 non-linear mapping we perform the following steps:
- 1.
- Use mmap() 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
start argument serves two purposes. First, it identifies the mapping
whose pages we want to rearrange. Thus,
start must be an address that
falls within a region previously mapped by a call to
mmap(). Second,
start specifies the address at which the file pages identified by
pgoff and
size will be placed.
The
prot argument must be specified as 0.
The
flags argument has the same meaning as for
mmap(), but all
flags other than MAP_NONBLOCK are ignored.
On success,
remap_file_pages() returns 0. On error, -1 is returned, and
errno is set appropriately.
The
remap_file_pages() system call appeared in Linux 2.5.46.
- EINVAL
- start does not refer to a valid mapping created with
the MAP_SHARED flag.
- EINVAL
- start, size, prot, or pgoff is
invalid.
The
remap_file_pages() system call is Linux specific.
getpagesize(2),
mmap(2),
mmap2(2),
mprotect(2),
mremap(2),
msync(2)
