— control the inheritance of
Standard C Library (libc, -lc)
, size_t len
() system call changes the specified pages to have
the inheritance characteristic inherit
. 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
is capable of adjusting inheritance
characteristics on a page basis. Inheritance only effects children created by
(). It has no effect on exec
processes replace their address space entirely. This system call also has no
effect on the parent's address space (other than to potentially share the
address space with its children).
Inheritance is a rather esoteric feature largely superseded by the
feature of mmap
However, it is possible to use minherit
() to share a block
of memory between parent and child that has been mapped
. That is, modifications made by parent or
child are shared but the original underlying file is left untouched.
- This option causes the address space in question to be
shared between parent and child. It has no effect on how the original
underlying backing store was mapped.
- This option prevents the address space in question from
being inherited at all. The address space will be unmapped in the
- This option causes the child to inherit the address space
as copy-on-write. This option also has an unfortunate side effect of
causing the parent address space to become copy-on-write when the parent
forks. If the original mapping was
will no longer be shared in the parent after the parent forks and there is
no way to get the previous shared-backing-store mapping without unmapping
and remapping the address space in the parent.
() function returns the value 0 if
successful; otherwise the value -1 is returned and the global variable
is set to indicate the error.
() system call will fail if:
- The virtual address range specified by the
addr and len arguments is not
- The flags specified by the inherit
argument were not valid for the pages specified by the
addr and len arguments.
() system call first appeared in
and then in FreeBSD
Once you set inheritance to
, there is no way to recover the original
copy-on-write semantics short of unmapping and remapping the area.