gem5'ers
There is an attractive instruction tracer "InstPBTrace" in gem5, but no
documentation on how to use it. I'm using gem5 for ARMv8.
Taking a guess by analogy with documentation on how to enable other instr
tracers, I hack into fs.py
cpu.tracer = InstPBTrace()
cpu.tracer.file_name = "/tmp/foo"
And that starts up the InstPBTracer, albeit briefly.
The tracer soon derails when it attempts to protobuf serialize an enumeration
value which is not valid for protobuf encodings. See the stack trace below.
Given the age of InstPBTrace, the lack of documentation, and the apparent
misfit between the internals of gem5 and the protobuf specification, I would
seem InstPBTrace is broken.
Here's the stack trace; frame1 argument 'value' with value of 47 is rejected by
Inst_InstType_IsValid.
0 ProtoMessage::Inst_InstType_IsValid (value=21845) at
build/ARM/proto/inst.pb.cc:224
#1 0x00005555592d3849 in ProtoMessage::Inst::set_type (this=0x55555c9b5aa0,
value=47) at build/ARM/proto/inst.pb.h:1143
#2 0x0000555559523c58 in Trace::InstPBTrace::traceInst (this=0x55555c8d9450,
tc=0x55555c3db0d0, si=..., pc=...)
at build/ARM/cpu/inst_pb_trace.cc:162
#3 0x00005555595232d9 in Trace::InstPBTraceRecord::dump (this=0x55555bbe9960)
at build/ARM/cpu/inst_pb_trace.cc:63
#4 0x00005555592e6e79 in BaseSimpleCPU::postExecute (this=0x55555e0e8000) at
build/ARM/cpu/simple/base.cc:657
#5 0x00005555592dcb5e in AtomicSimpleCPU::tick (this=0x55555e0e8000) at
build/ARM/cpu/simple/atomic.cc:733
#6 0x00005555592d8f7d in AtomicSimpleCPU::<lambda()>::operator()(void) const
(__closure=0x55555e0e8458) at build/ARM/cpu/simple/atomic.cc:81
#7 0x00005555592dd164 in std::_Function_handler<void(),
AtomicSimpleCPU::AtomicSimpleCPU(AtomicSimpleCPUParams*)::<lambda()>
>::_M_invoke(const std::_Any_data &) (__functor=...) at
/usr/include/c++/9/bits/std_function.h:300
#8 0x000055555721781e in std::function<void ()>::operator()() const
(this=0x55555e0e8458) at /usr/include/c++/9/bits/std_function.h:690
#9 0x0000555557216a14 in EventFunctionWrapper::process (this=0x55555e0e8420)
at build/ARM/sim/eventq.hh:836
#10 0x0000555557519095 in EventQueue::serviceOne (this=0x55555bf9bf20) at
build/ARM/sim/eventq.cc:228
#11 0x0000555557523b1c in doSimLoop (eventq=0x55555bf9bf20) at
build/ARM/sim/simulate.cc:219
#12 0x000055555752372e in simulate (num_cycles=18446744073709551615) at
build/ARM/sim/simulate.cc:132
#13 0x0000555557356652 in pybind11::detail::argument_loader<unsigned
long>::call_impl<GlobalSimLoopExitEvent*, GlobalSimLoopExitEvent* (*&)(unsigned
long), 0ul, pybind11::detail::void_type> (this=0x7fffffffd288,
f=@0x55555bc295b8: 0x5555575233f4 <simulate(unsigned long)>)
at ext/pybind11/include/pybind11/cast.h:1935
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