About The Instruction Memory Barrier Operation - ARM ARM926EJ-S Technical Reference Manual

Instruction Memory Barrier
9.1

About the instruction memory barrier operation

9-2
Whenever code is treated as data, for example self-modifying code, or loading code into
memory, then a sequence of instructions called an Instruction Memory Barrier (IMB)
operation must be used to ensure consistency between the data and instruction streams
processed by the ARM926EJ-S processor.
Usually the instruction and data streams are considered to be completely independent
by the ARM926EJ-S processor memory system, and any changes in the data side are
not automatically reflected in the instruction side. For example if code is modified in
main memory then the ICache might contain stale entries. To remove these stale entries
part or all of the ICache must be invalidated.
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