Performance Counter Addresses

Downing, Evan P edowning3 at gatech.edu
Fri Oct 2 16:51:31 UTC 2015


Hello all,


I have looked through the previous threads on this mailing list and have not found this question, but many apologies of this has already been discussed.


I am interested in using Mozilla rr on an older version of QEMU.


Of course the problem with this is that rr needs a processor in order to work properly, so the emulated CPU must be well-implemented.


For this QEMU version (1.0.1), I can only use core2duo (which I believe to be synonymous with "Intel Merom" in your source code) as my processor for rr, as the other processors are too out of date for rr to use.


A list of CPUs I can use with this version of QEMU are:

  *   x86           [n270]
  *   x86         [athlon]
  *   x86       [pentium3]
  *   x86       [pentium2]
  *   x86        [pentium]
  *   x86            [486]
  *   x86        [coreduo]
  *   x86          [kvm32]
  *   x86         [qemu32]
  *   x86          [kvm64]
  *   x86       [core2duo]
  *   x86         [phenom]
  *   x86         [qemu64]

In order to make this work with rr, I need addresses for retired conditional branches, retired instructions, and hardware interrupts.

In your source code (https://github.com/mozilla/rr/blob/master/src/PerfCounters.cc#L58) you state that these addresses should only be modified if we know what we are doing.

I also read in your presentation that these addresses just require work/time to find.


Would you mind telling me how to go about finding these addresses for "Intel Merom" and if this idea of mine will even work for rr?


Thanks,

Evan

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