Hi Tor,

Running through the ETMv3 decode is making me think a bit more about the generic output packets. For ETMv4, we output a OCSD_GEN_TRC_ELEM_PE_CONTEXT to indicate context info for the core, then a string of OCSD_GEN_TRC_ELEM_INSTR_RANGE for the instructions executed with the context. This mirrors the way ETMv4 packet streams work.

ETMv3 and to a lesser extent PTM handles context differently, meaning we have to work harder to output the a OCSD_GEN_TRC_ELEM_PE_CONTEXT prior to the OCSD_GEN_TRC_ELEM_INSTR_RANGE packets.

It occurs to me that the context packet is only really relevant when processing the instruction ranges (and possibly for data tracing later on), so I was considering:- 1) Mandating that the context part of the generic packet structure is valid for the instruction range packet (it happens to be for the current decoder, but that is a consequence of how it is written rather than a deliberate rule). In future it can be mandated for data packets if required. 2) Dropping the OCSD_GEN_TRC_ELEM_PE_CONTEXT packets completely.

For the decoders this mandate is not onerous as they have to maintain the current context anyway to do the decode. Dropping a packet could simplify both decoder and library client operation.

How would this affect the current perf decode?

After the ETMv3 dev (or possibly at the end of it), I am going to expand the docs for the generic packets to set down these rules and dependencies.

Regards

Mike

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