While executing the tools on target tests we discovered an issue when executing the "powertop --calibrate" command. Basically, after the calibration starts and a few steps are finished the calibration sequence freezes at the following step:
"Calibrating: CPU wakeup power consumption". 

root@qemuppc:~# powertop --calibrate
Cannot load from file /var/cache/powertop/saved_results.powertop
Cannot load from file /var/cache/powertop/saved_parameters.powertop
RAPL device for cpu 0
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
RAPL device for cpu 0
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Model-specific registers (MSR)                   not found (try enabling CONFIG_X86_MSR).
Cannot load from file /var/cache/powertop/saved_parameters.powertop
Starting PowerTOP power estimate calibration
Calibrating idle
  function ktime_to_ns not defined
Calibrating: disk usage
Calibrating backlight
Calibrating idle
Calibrating: CPU usage on 1 threads
Calibrating: CPU usage on 4 threads
Calibrating: CPU wakeup power consumption
Calibrating: CPU wakeup power consumption
Calibrating: CPU wakeup power consumption


If the calibration process is stopped (ctrl+c) the target behaves strangely: it either freezes or it takes a lot of times to run any command (other tests may fail, like perf --time=x if the target is used after the calibration issue).