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Patent Title: Tracing technique for application programs using protect mode addressing

Assignee: IBM
Patent Number: US5701486
Issue Date: 12-23-1997
Application Number:
File Date:12-08-1993

Abstract: A tracing technique is disclosed for an application program that is only permitted to access virtual storage, not physical storage, via a Protect Mode Addressing scheme. The application program contains an initialization statement that initializes a trace address T1 to be equal to a virtual address V1 contained in a data area under the control of the application program. A statement in the application program then requests a pinned virtual address V2 that maps to a predetermined physical address P from a device driver. If the device driver exists, the trace address T1=virtual address V2. A memory mapper maps address V2 to physical address P and writes the information to physical address P. A conventional logic analyzer monitors the bus for any writes to physical address P and captures the contents of the bus upon the detection of this condition.


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IBM Pledge dated 1/11/2005