Provided by: manpages-dev_2.17-1_all
remap_file_pages - create a non-linear file mapping
int remap_file_pages(void *start, size_t size, int prot, ssize_t pgoff,
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 values specified in start 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(), 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
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)