For example under KVM it was failing as

    cpu:	Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz
    cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq: No such file or directory
      File "<string>", line 1
        print '%.2fGHz' % ( / 1E6)
                            ^
    SyntaxError: invalid syntax

    $ lscpu
    Architecture:        x86_64
    CPU op-mode(s):      32-bit, 64-bit
    Byte Order:          Little Endian
    Address sizes:       40 bits physical, 48 bits virtual
    CPU(s):              40
    On-line CPU(s) list: 0-39
    Thread(s) per core:  1
    Core(s) per socket:  1
    Socket(s):           40
    NUMA node(s):        1
    Vendor ID:           GenuineIntel
    CPU family:          6
    Model:               63
    Model name:          Intel(R) Xeon(R) CPU E5-2678 v3 @ 2.50GHz
    Stepping:            2
    CPU MHz:             2494.238
    BogoMIPS:            4988.47
    Virtualization:      VT-x
    Hypervisor vendor:   KVM
    Virtualization type: full
    L1d cache:           32K
    L1i cache:           32K
    L2 cache:            4096K
    L3 cache:            16384K
    NUMA node0 CPU(s):   0-39
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single pti tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat

-> Fix it by checking whether cpufreq/cpuidle directories are available, and display "?" if they are not.