An addressing method and computer system for sharing a large memory address space using address space within an operating system's virtual address space. The system provides sharing the SSB over many processes without the disadvantages associated with process based global sections. For instance, the novel system does not require that each process maintain its own dedicated page table entries (PTEs) in order to access the SSB thereby requiring less operating system virtual memory to maintain the PTE data structures. The system uses a process to switch to kernel mode, then identifies those sections of the operating system virtual memory space that are not being used; in some cases the unused address space can be 1.5-1.8 gigabytes in size. The unused address space is linked together to form the SSB. The system alters the privileges of the PTEs corresponding to the SSB so that user mode processes can access this usually protected operating system virtual memory space. The result is a statically mapped large memory address buffer (SSB) that can be immediately shared by all processes within the computer system while consuming only a single statically mapped PTE which all processes can use. In one example, 500 processes mapping to a 2 gigabyte SSB requires only 2 megabytes of memory storage for the corresponding PTEs, assuming conventional memory page sizes. In one example, the SSBs are allocated from a system space virtual memory map which is 2 gigabytes in size in a 32-bit VMS operating system.
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