A method, system, apparatus, and computer program product is presented for
tracing operations. A set of related methodologies can be used within
instruction tracing software, such as a tracing program, to reduce its
tendency to generate interrupts that cause unwanted effects in the system
that is being captured. A first methodology allows access to protected
memory blocks so that instructions may be read from those memory blocks.
A second methodology provides for the trace output buffer to be accessed
using physical addressing. A third methodology traces only instruction
addresses, which are resolved later during a post-processing phase of
operation. A fourth methodology comprises multiple different methods for
obtaining copies of instructions that have already executed rather than
obtaining them before they are executed.