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gem5: start to document tracer internals

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Ciro Santilli 六四事件 法轮功
2019-07-23 00:00:01 +00:00
parent 361b94f2df
commit 9252f53180
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README.adoc
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@@ -9994,6 +9994,60 @@ TODO that format is either buggy or is very difficult to understand:
https://stackoverflow.com/questions/54882466/how-to-use-the-tarmac-tracer-with-gem5 https://stackoverflow.com/questions/54882466/how-to-use-the-tarmac-tracer-with-gem5
===== gem5 tracing internals
As of gem5 16eeee5356585441a49d05c78abc328ef09f7ace the default tracer is `ExeTracer`. It is set at:
....
src/cpu/BaseCPU.py:63:default_tracer = ExeTracer()
....
which then gets used at:
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class BaseCPU(ClockedObject):
[...]
tracer = Param.InstTracer(default_tracer, "Instruction tracer")
....
All tracers derive from the common `InstTracer` base class:
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git grep ': InstTracer'
....
gives:
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src/arch/arm/tracers/tarmac_parser.hh:218: TarmacParser(const Params *p) : InstTracer(p), startPc(p->start_pc),
src/arch/arm/tracers/tarmac_tracer.cc:57: : InstTracer(p),
src/cpu/exetrace.hh:67: ExeTracer(const Params *params) : InstTracer(params)
src/cpu/inst_pb_trace.cc:72: : InstTracer(p), buf(nullptr), bufSize(0), curMsg(nullptr)
src/cpu/inteltrace.hh:63: IntelTrace(const IntelTraceParams *p) : InstTracer(p)
....
As mentioned at <<gem5-tarmac-traces>>, there appears to be no way to select those currently without hacking the config scripts.
TARMAC is described at: <<gem5-tarmac-traces>>.
TODO: are `IntelTrace` and `TarmacParser` useful for anything or just relics?
Then there is also the `NativeTrace` class:
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src/cpu/nativetrace.hh:68:class NativeTrace : public ExeTracer
....
which gets implemented in a few different ISAs, but not all:
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src/arch/arm/nativetrace.hh:40:class ArmNativeTrace : public NativeTrace
src/arch/sparc/nativetrace.hh:41:class SparcNativeTrace : public NativeTrace
src/arch/x86/nativetrace.hh:41:class X86NativeTrace : public NativeTrace
....
TODO: I can't find any usages of those classes from in-tree configs.
=== QEMU GUI is unresponsive === QEMU GUI is unresponsive
Sometimes in Ubuntu 14.04, after the QEMU SDL GUI starts, it does not get updated after keyboard strokes, and there are artifacts like disappearing text. Sometimes in Ubuntu 14.04, after the QEMU SDL GUI starts, it does not get updated after keyboard strokes, and there are artifacts like disappearing text.