To Enable/Disable The Instruction And Data Caches - HP MC68040 User Manual

Chapter 8: Configuring the Emulator
Configuring the Emulator General Items Screen

To enable/disable the instruction and data caches

• Choose "Yes" or "No" for the "Enable Instruction/Data Caches" configuration
option.
Choosing "Yes" allows the instruction and data caches to be enabled. With this
choice, the caches can still be disabled in selected memory ranges as specified
when mapping memory.
Choosing "No" causes the emulator to assert the CDIS signal to prevent
instructions and data from being loaded into the respective caches during target
program execution. This overrides any specifications you may make for individual
entries on the memory map.
When you disable the instruction and data caches, all activity appears on the
emulation processor buses where it can be monitored and captured by the
emulation-bus analyzer. When you allow the caches to be enabled, program
execution is faster, but only partial information is available to be traced by the
emulation-bus analyzer. This may cause confusing trace displays or failure to
trigger, especially if the code being analyzed is a small loop where all the
instructions and operands fit into cache and registers.
When you are more concerned about measuring processor performance, you should
enable the caches. If you are making analyzer measurements at the same time, you
may need to experiment to find suitable trigger combinations.
If you need to disable caching only for accesses to a specific memory block, enter
that as part of your specification when defining the corresponding memory map
term. This allows you to capture analysis information for specific memory ranges
without dramatically affecting overall system performance.
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