mctl(3BSD) (BSD System Compatibility) mctl(3BSD)
NAME
mctl - (BSD) memory management control
SYNOPSIS
/usr/ucb/cc [flag . . . ] file . . .
#include <sys/types.h>
#include <sys/mman.h>
mctl(caddr_t addr, size_t len, int function, void *arg);
DESCRIPTION
mctl applies a variety of control functions over pages
identified by the mappings established for the address range
[addr, addr + len]. The function to be performed is
identified by the argument function. Valid functions are
defined in mman.h as follows.
MC_LOCK
Lock the pages in the range in memory. This function is
used to support mlock. See mlock(3C) for semantics and
usage. arg is ignored.
MC_LOCKAS
Lock the pages in the address space in memory. This
function is used to support mlockall. See mlockall(3C)
for semantics and usage. addr and len are ignored. arg
is an integer built from the flags:
MCL_CURRENT Lock current mappings
MCL_FUTURE Lock future mappings
MC_SYNC
Synchronize the pages in the range with their backing
storage. Optionally invalidate cache copies. This
function is used to support msync. See msync(3C) for
semantics and usage. arg is used to represent the flags
argument to msync. It is constructed from an OR of the
following values:
MS_SYNC Synchronized write
MS_ASYNC Return immediately
MS_INVALIDATE Invalidate mappings
MS_ASYNC returns after all I/O operations are scheduled.
MS_SYNC does not return until all I/O operations are
complete. Specify exactly one of MS_ASYNC or MS_SYNC.
MS_INVALIDATE invalidates all cached copies of data from
memory, requiring them to be re-obtained from the
object's permanent storage location upon the next
Copyright 1994 Novell, Inc. Page 1
mctl(3BSD) (BSD System Compatibility) mctl(3BSD)
reference.
MC_UNLOCK
Unlock the pages in the range. This function is used to
support munlock. See mlock(3C) for semantics and usage.
arg is ignored.
MC_UNLOCKAS
Remove address space memory lock, and locks on all
current mappings. This function is used to support
munlockall [see mlockall(3C)]. addr and len must have
the value 0. arg is ignored.
RETURN VALUE
mctl returns 0 on success, -1 on failure.
ERRORS
mctl fails if:
EAGAIN Some or all of the memory identified by
the operation could not be locked due to
insufficient system resources.
EBUSY MS_INVALIDATE was specified and one or
more of the pages is locked in memory.
EFAULT The page to be locked has been aborted
(for example, by a file truncate
operation), or pages following the end of
an object are not allocated.
EINVAL addr is not a multiple of the page size as
returned by getpagesize.
EINVAL addr and/or len do not have the value 0
when MC_LOCKAS or MC_UNLOCKAS are
specified.
EINVAL arg is not valid for the function
specified.
EIO An I/O error occurred while reading from
or writing to the file system.
Copyright 1994 Novell, Inc. Page 2
mctl(3BSD) (BSD System Compatibility) mctl(3BSD)
ENOMEM Addresses in the range [addr, addr + len]
are invalid for the address space of a
process, or specify one or more pages
which are not mapped.
EPERM The process's effective user ID is not
super-user and one of MC_LOCK, MC_LOCKAS,
MC_UNLOCK, or MC_UNLOCKAS was specified.
REFERENCES
getpagesize(3BSD), mlock(3C), mlockall(3C), mmap(2), msync(3C)
Copyright 1994 Novell, Inc. Page 3