- memory management control
/usr/ucb/cc [ flag ... ] file ... #include <sys/types.h> #include <sys/mman.h> int mctl(addr, len, function, arg) caddr_t addr; size_t len; int function; int arg;
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:
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.
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:
Lock current mappings
Lock future mappings
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_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 reference.
Unlock the pages in the range. This function is used to support munlock(). arg is ignored.
Remove address space memory lock, and locks on all current mappings. This function is used to support munlockall(). addr and len must have the value 0. arg is ignored.
mctl() returns 0 on success, -1 on failure.
mctl() fails if:
Some or all of the memory identified by the operation could not be locked due to insufficient system resources.
MS_INVALIDATE was specified and one or more of the pages is locked in memory.
addr is not a multiple of the page size as returned by getpagesize().
addr and/or len do not have the value 0 when MC_LOCKAS or MC_UNLOCKAS are specified.
arg is not valid for the function specified.
An I/O error occurred while reading from or writing to the file system.
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.
The process's effective user ID is not superuser and one of MC_LOCK MC_LOCKAS, MC_UNLOCK, or MC_UNLOCKAS was specified.
Use of these interfaces should be restricted to only applications written on BSD platforms. Use of these interfaces with any of the system libraries or in multi-thread applications is unsupported.