20 lines
1.0 KiB
Plaintext
20 lines
1.0 KiB
Plaintext
* ETMv4/PTM - decoder updates to handle advanced configuration.
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-> Certain (currently unused by perf / current hardware) configuration settings
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can alter the format of the trace output. One example is Return Stack -
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settable in the control registers for PTM/ETMv4, and removes some inline
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addresses. Decoder must use a follower to correctly trace when this is set.
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* ITM packet processing and decode.
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-> ITM is primarily an M class SW trace module. I wouldn't expect to see it on
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systems with STM, unless a companion M class was present.
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*Data trace - ETMv4 / ETMv3
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-> Differing solutions to data trace in v4/v3 - v4 is separate trace stream
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completely, output at trace ID <instruction_trace_ID>+1. ETMv3 is inline with
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the instruction trace.
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Cortex-A cores do not support this architecturally. On R and M profile cores it
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is an option. There are scenarios in future that could see linux on R cores, plus
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on something like Juno it is possible to switch on trace for the SCP
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(M class processor). So at some point data trace may be required.
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