Memory management

SCO OpenServer includes a complete set of memory-mapping mechanisms. Process address spaces are composed of a vector of memory pages, each of which can be independently mapped and manipulated. The memory-management facilities

• unify the system's operations on memory

• provide a set of kernel mechanisms powerful and general enough to support the implementation of fundamental system services without special-purpose kernel support

• maintain consistency with the existing environment, in particular using the SCO OpenServer file system as the name space for named virtual-memory objects

The system's virtual memory consists of all available physical memory resources including local and remote file systems, processor primary memory, swap space, and other random-access devices. Named objects in the virtual memory are referenced though the SCO OpenServer file system. However, not all file system objects are in the virtual memory; devices that SCO OpenServer cannot treat as storage, such as terminal and network device files, are not in the virtual memory. Some virtual memory objects, such as private process memory and shared memory segments, do not have names.

The memory mapping interface

The applications programmer gains access to the facilities of the virtual memory system through several sets of system calls.

• mmap establishes a mapping between a process's address space and a virtual memory object.

• mprotect assigns access protection to a block of virtual memory.

• munmap removes a memory mapping.

• mincore tells whether mapped memory pages are in primary memory.

Where to find more information

See ``Process management'' for a detailed description of the virtual memory system. Refer to mmap(S), mprotect(S), munmap(S), and mincore(S).