Sun Microsystems, Inc.

Ray Cheng

John E Watkins

William A Shannon

Joseph F Moran

William Van Loo

William N Joy

Robert Barton Garner

Kenneth S Bower

Stackable, interlocking totem moss pole with stake

Hardware and software improvements in workstations which utilize virtual addressing in multi-user operating systems with write back caches, including operating systems which allow each user to have multiple active processes. In virtual addressing, multi-user workstations, system performance may be improved significantly by including a virtual address write back cache as one of the system elements. Data protection and the reassignment of virtual addresses are supported within such a system as well. Multiple active processes, each with its own virtual address space, and an operating system shared by those processes in a manner which is invisible to user programs. Cache 'Flush' logic is used to remove selected blocks from the virtual cache when virtual addresses are to be reassigned.

Virtual address write back cache with address reassignment and cache

Improvements in workstations which utilizes virtual addressing in multi-user operating systems with write back caches, including operating systems which allow each user to have multiple active processes directed to the support of alias addresses, i.e., two or more virtual addresses which map to the same physical address in real memory Specifically, alias addresses are created so that their low order address bits are identical, modulo the size of the cache (as a minimum) for user programs which use alias addresses generated by the kernel, or wholely within the kernel. For alias addresses in the operating system, rather than user programs, which cannot be made to match in their low order address bits, their pages are assigned as 'Don't Cache' pages in the memory management unit (MMU) employed by workstations which utilize virtual addressing.

Alias address support

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Cupertino, CA, United States of America

Ray Cheng