NAME
minherit —
control the inheritance of
pages
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/mman.h>
int
minherit(
void
*addr,
size_t len,
int inherit);
DESCRIPTION
The
minherit() system call changes the specified range of
virtual addresses to have the inheritance characteristic
inherit, which determines how
fork(2) will map the region in the
child process. The supported inheritance characteristics are:
-
-
- MAP_INHERIT_COPY
- The child is given a private copy of the region: writes
from parent or child are not seen by the other.
-
-
- MAP_INHERIT_NONE
- The region is unmapped in the child.
-
-
- MAP_INHERIT_SHARE
- The child is shares the region with the parent: writes from
parent and child are seen by both.
-
-
- MAP_INHERIT_ZERO
- The region is mapped in the child to anonymous pages filled
with zeros.
Normally, the parent's virtual address space is copied for the child as if with
MAP_INHERIT_COPY
, for which the alias
MAP_INHERIT_DEFAULT
is provided. Regions in the parent
mapped using
mmap(2) with the
MAP_SHARED
flag are by default shared with the child
as if with
MAP_INHERIT_SHARED
.
Not all implementations will guarantee that the inheritance characteristic can
be set on a page basis; the granularity of changes may be as large as an
entire region.
RETURN VALUES
The
minherit() function returns the value 0 if
successful; otherwise the value -1 is returned and the global variable
errno is set to indicate the error.
ERRORS
minherit() will fail if:
-
-
- [
EINVAL
]
- An invalid region or invalid parameters were
specified.
SEE ALSO
fork(2),
madvise(2),
mincore(2),
mmap(2),
mprotect(2),
msync(2),
munmap(2)
HISTORY
The
minherit() function first appeared in
OpenBSD.
BUGS
If a particular port does not support page-granularity inheritance, there's no
way to figure out how large a region is actually affected by
minherit().