title: HOW TO FORCEFULLY DISABLE intel_pstate? intel_pstate is enabled on reboot even with intel_pstate=disable option in grub
body: <p>I am trying to use cpu-frequency scaling to set cpu frequency. In my system, only powersave , performance frequency-scaling-governor supported. It was explained in other document, by default, intel_pstate is enabled and it only supports powersave , performance frequency-scaling-governor and solution is disable intel_pstate. 
  So I tried to disable as below </p>
  
  <pre><code>sudo nano /etc/default/grub
  GRUB_CMDLINE_LINUX_DEFAULT="intel_pstate=disable"
  sudo update-grub
  </code></pre>
  
  <p><strong>on reboot, intel_pstate is enabled.</strong></p>
  
  <p>so , again I made following changes in grub</p>
  
  <pre><code>sudo nano /etc/default/grub
  
  GRUB_CMDLINE_LINUX_DEFAULT="intel_pstate=disable acpi=force"
  sudo update-grub
  </code></pre>
  
  <p><strong>on reboot, it still shows intel_pstate is enabled.</strong></p>
  
  <p>when I execute following command,</p>
  
  <pre><code>$ cpupower -c all frequency-info
  
      analyzing CPU 7:
        driver: intel_pstate
        CPUs which run at the same hardware frequency: 7
        CPUs which need to have their frequency coordinated by software: 7
        maximum transition latency:  Cannot determine or is not supported.
        hardware limits: 1.60 GHz - 3.90 GHz
        available cpufreq governors: performance powersave
        current policy: frequency should be within 1.60 GHz and 3.90 GHz.
                        The governor "powersave" may decide which speed to use
                        within this range.
        current CPU frequency: 1.72 GHz (asserted by call to hardware)
        boost state support:
          Supported: yes
          Active: yes
          25500 MHz max turbo 4 active cores
          25500 MHz max turbo 3 active cores
          25500 MHz max turbo 2 active cores
          25500 MHz max turbo 1 active cores
  
       $ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
       intel_pstate
  
  
     $ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors 
      performance powersave
  </code></pre>
  
  <p><strong>As userspace governor is not available, I am unable to use cpu-frequency scaling (cpupower ).</strong></p>
  
  <p>I am using Intel Core-i7 @3.40GHZ, Linux debian-8.0 (kernel- 3.16.35 ).</p>
  
  <p>It will be a great help if you can help me to resolve this problem. 
  Thank you in advance.</p>
  
  <p><strong>EDIT 1:</strong></p>
  
  <p>As per suggestion of Peter Cordes,I make manual entry during boot time and now <strong>intel_pstate is disabled, but no cpu frequency governor or acpi cpufrequency driver not activated.</strong></p>
  
  <pre><code>root@debian:~# cpupower -c 0 frequency-info
  analyzing CPU 0:
    no or unknown cpufreq driver is active on this CPU
    CPUs which run at the same hardware frequency: Not Available
    CPUs which need to have their frequency coordinated by software: Not Available
    maximum transition latency:  Cannot determine or is not supported.
    hardware limits: Not Available
    available cpufreq governors: Not Available
    Unable to determine current policy
    current CPU frequency: Unable to call hardware
    current CPU frequency:  Unable to call to kernel
    boost state support:
      Supported: yes
      Active: yes
      25500 MHz max turbo 4 active cores
      25500 MHz max turbo 3 active cores
      25500 MHz max turbo 2 active cores
      25500 MHz max turbo 1 active cores
  </code></pre>
  
  <p>As no cpu frequency governor available, I am not able to set cpu frequency. I got following error messages when I try to set cpu frequency.</p>
  
  <pre><code>root@debian:~# cpupower -c 0 frequency-set -f 2000000
  Setting cpu: 0
  Error setting new values. Common errors:
  - Do you have proper administration rights? (super-user?)
  - Is the governor you requested available and modprobed?
  - Trying to set an invalid policy?
  - Trying to set a specific frequency, but userspace governor is not available,
     for example because of hardware which cannot be set to a specific frequency
     or because the userspace governor isn't loaded?
  </code></pre>