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remap_file_pages() - Unix, Linux System Call
remap_file_pages - create a non-linear file mapping
int remap_file_pages(void *start, size_t size, int prot, ssize_t pgoff, int flags);
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
The advantage of using
remap_file_pages() over using repeated calls to
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:
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.
mmap() to create a mapping (which is initially linear).
This mapping must be created with the
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.
start argument serves two purposes.
First, it identifies the mapping whose pages we want to rearrange.
start must be an address that falls within
a region previously mapped by a call to
start specifies the address at which the file pages
size will be placed.
The values specified in
size should be multiples of the system page size.
If they are not, then the kernel rounds
down to the nearest multiple of the page size.
prot argument must be specified as 0.
flags argument has the same meaning as for
mmap(), but all flags other than
MAP_NONBLOCK are ignored.
remap_file_pages() returns 0.
On error, -1 is returned, and
errno is set appropriately.
remap_file_pages() system call appeared in Linux 2.5.46.
start does not refer to a valid mapping
created with the
start, size, prot, or
pgoff is invalid.
remap_file_pages() system call is Linux specific.