Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
1998-11-06
2001-07-31
Ray, Gopal C. (Department: 2181)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C710S052000
Reexamination Certificate
active
06269454
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to debugging of software for processor-oriented systems, and more particularly to maintaining object information concurrent with data optimization.
2. Description of the Related Art
In order to improve performance of a processor-oriented system, there has been an effort to decouple processor performance from the limitations of system bus performance. This effort has been pursued by providing a write buffer to control access to a system resource of a processor-oriented system. Read operations are normally given the highest priority for access to a system bus. Other accesses to a system bus such as write operations result in a delay of write data in a write buffer until the system bus becomes available.
A write buffer has increasingly been provided in processor-oriented systems to perform data optimization operations such as write merging, write collapsing, and read merging for maintaining data coherency. One candidate for queuing in a write buffer is a write object value. As a result of data optimization operations involving write object values, object size information for write object values has been lost. That is, the optimized object values no longer accompany the corresponding object size information. For example, if a write buffer merges two consecutive byte-sized object values into a single word-sized object value, then the write buffer loses the object size of the original object values, as the new data object is word-sized rather than byte-sized.
The object size information lost as a result of data optimization operations has been a limiting factor in debugging a software program of a processor-oriented system. A software program executed by a processor-oriented system has been used to perform write operations on data objects. When a software program does not utilize data optimization, the software program has typically been debugged by tracing or tracking write object values resulting from write operations. Reconstruction of write object values in debugging a software program, however, has been constrained by data optimization operations by a write buffer. A write object value resulting from a data optimization operation bas lacked the object size information necessary to reconstruct pre-optimization write object values.
SUMMARY OF THE INVENTION
Briefly, a debugging environment in accordance with the present invention maintains object information concurrent with data optimization operations by a write buffer of a target system. Within the target system, a system bus is coupled between a system memory and a microcontroller. A data optimization operation by the write buffer is detected by monitoring of a merge signal of the system bus by a bus monitoring device. When a data optimization operation is detected, data optimization attributes (e.g., object information, data, and address) associated with the data optimization operation are captured in the form of an object information signal responsive to a capture signal from the bus monitoring device. The data optimization attributes may be stored in either a trace cache of the target system or a memory of external trace capture equipment connected to the debug port, or a memory of the bus monitoring device. In providing the data optimization attributes external to the microcontroller, the data optimization attribute may be temporarily held by trace pins of a debug port of the microcontroller. The data optimization attributes may be extracted from the object information signal and processed by the external trace capture equipment or the bus monitoring device. By processing the data optimization attributes, pre-optimization write object values may be reconstructed.
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International Search Report, PCT/US99/14816, Oct. 28, 1999, 3 pp.
Godfrey Gary M.
Mann Daniel P.
Advanced Micro Devices , Inc.
Akin Gump Strauss Hauer & Feld L.L.P.
Ray Gopal C.
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