Microprocessor architecture including unified cache debug unit

Abstract

A microprocessor architecture including a unified cache debug unit. A debug unit on the processor chip receives data / command signals from a unit of the execute stage of the multi-stage instruction pipeline of the processor and returns information to the execute stage unit. The cache debug unit is operatively connected to both instruction and data cache units of the microprocessor. The memory subsystem of the processor may be accessed by the cache debug unit through either of the instruction or data cache units. By unifying the cache debug in a separate structure, the need for redundant debug structure in both cache units is obviated. Also, the unified cache debug unit can be powered down when not accessed by the instruction pipeline, thereby saving power.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to provisional application No. 60 / 572,238 filed May 19, 2004, entitled “Microprocessor Architecture,” hereby incorporated by reference in its entirety.FIELD OF THE INVENTION [0002] This invention relates generally to microprocessor architecture and more specifically to an improved cache debug unit for a microprocessor. BACKGROUND OF THE INVENTION [0003] A major focus of microprocessor design has been to increase effective clock speed through hardware simplifications. Exploiting the property of locality of memory references, cache memories have been successful in achieving high performance in many computer systems. In the past, cache memories of microprocessor-based systems were provided off-chip using high performance memory components. This was primarily because the amount of silicon area necessary to provide an on-chip cache memory of reasonable performance would have been impractical. Increasing the s...

AI Technical Summary

Benefits of technology

[0010] Various embodiments of the invention are disclosed that overcome one or more of the shortcomings of conventional microprocessors through a microprocessor architecture having a unified cache debug unit. In these embodiments, a separate cache debug unit is provided which serves as an interface to both the instruction cache and the data cache. In various exemplary embodiments, the cache debug has shared hardware logic accessible to both the instruction cache and the data cache. In various exemplary embodimen

Problems solved by technology

This was primarily because the amount of silicon area necessary to provide an on-chip cache memory of reasonable performance would have been impractical.

Increasing the size of an integrated circuit to accommodate a cache memory adversely impacts the yield of the integrated circuit in a given manufacturing process.

Both a cache miss and an uncacheable memory reference result in an access to the main memory.

However, observing the program flow of processors having cache integrated on-chip is much more difficult because most of the processing operations are performed internally within the chip.

Due to difficulties in interfacing with the on-chip cache, debugging systems have also had to move onto the chip.

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