Apple Inc.

Martin Scheinberg

Joseph Sokol, Jr

Christopher G Peak

Embodiments of the present invention provide a system that maps an N-bit application to virtual memory. The N-bit application may be obtained by porting an M-bit application to an N-bit architecture where N is greater than M. During operation, the system receives a request to map an N-bit application to a computer's virtual memory. The system then maps the N-bit application to a section of virtual memory which begins at a memory address that is greater than or equal to 2. If the N-bit application accesses a memory address which is less than 2, the system can generate a trap, thereby facilitating the discovery of M-bit memory references in the N-bit application.

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One embodiment of the present invention provides a system that uses an M-bit operating system (OS) kernel to support N-bit user processes. During operation, the system receives an exception. Note that the exception can be any event that needs to be handled by executing OS kernel code. Specifically, the exception can be a hardware interrupt, a software interrupt, an asynchronous interrupt, a synchronous interrupt, a signal, a trap, or a system call. Next, the system handles the exception by first switching the processor to the M-bit mode, and then executing M-bit OS kernel code which is designed to handle the exception. Note that the processor may primarily be designed to operate in the N-bit mode; the M-bit mode may primarily be provided for backward compatibility reasons.

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Morganville, NJ, United States of America

Martin Scheinberg