CPU Undervolting with Ubuntu 12.04

Hi guys,

PHC stands for Processor Hardware Control and, as it's easy to understand, it allows users to customize some features of CPU control in a linux environment, as undervolting.


So what do we need? An Ubuntu (or Debian) box, usually undervolting is useful on laptops: it enhance battery duration and reduces the heat production. You will also need some time and patience, ;]

1. You will need a kernel patch and a particular CPU driver so that the hardware control will be possible. First let's add the repo:
   

   sudo add-apt-repository ppa:linux-phc/ppa
   sudo add-apt-repository ppa:linux-phc/testing
   sudo apt-get update

2. Now let's install the kernel and its headers:
   

   sudo apt-get install linux-generic-phc linux-headers-generic-phc

   First pause... restart your PC and be sure to choose your new *-phc kernel.
3. As we will need to compile some stuff some Ubuntu users might need
   

   sudo apt-get install gtk2-engines-pixbuf python-gtk2-dev  build-essential

   And then:
   

   sudo apt-get install dkms debhelper

   Before doing anything else we have to create an empty file to match dmks autoconfiguration: Intel users go with the first, AMD with the second line!

   sudo sh -c 'echo >> /etc/modprobe.d/phc-intel.conf'
   sudo sh -c 'echo >> /etc/modprobe.d/phc-k8.conf'
4. Now you have to download the driver, choose it looking at your CPU: there are two choices AMD and Intel, be sure to take the right one.
5. Unpack the package to a temporary folder. Open a terminal and move there:

   cd **your_path**

   Intel users can generate a debian package:

   make dkms_mkdeb

   And install the resulting .deb package:

   sudo dpkg -i phc-intel-dkms_0.3.2_all.deb

   While AMD can't generate it, so:

   sudo make dkms_install 

   Now you have your driver ready to go!
6. So we will unload the old driver:
   

   sudo modprobe -r acpi-cpufreq

   Once you're done load the new one, amd users will have the second line, intel the first!
   

   sudo modprobe phc-intel
   sudo modprobe phc-k8

   If you experience the error: "FATAL: Module acpi_cpufreq is in use." you'll need to:
   

   sudo sh -c ' echo "\n#blackist required to load phc drivers
   blacklist acpi_cpufreq
   blacklist cpufreq_stats" > /etc/modprobe.d/blacklist.conf'
   sudo sh -c ' echo "modprobe ##your module##" > /etc/modules'

   And REBOOT =_= ...
7. Now I guess you want a cool GUI to easier setting VIDs: get it here. Unpack it to a non temporary folder and move there.
8. From the main phctool folder run:
   

   sudo ./install.sh

9. Follow the instruction (both yes will be OK)
10. Create a new program link in the menu with "Main Menu" to the command /**your_path**/pchtool.sh
11. Be sure to create a startup entry with the command
    

    /**your_path**/phctray.sh

    So voltages will be restored at each startup! 

After this installation procedure try to launch phctool from the main menu: there you can set the voltages and see many infos about your CPU. If it happens that you can't refresh the actual values install msr-tools and run it with:

sudo apt-get install msr-tools
sudo modprobe msr

The correct undervolted values are not universal, so you'll need some testing. If you think you'll need a guide, then take a look here:

http://linuxsolver.blogspot.com/2011/10/how-to-set-cpu-voltage.html


Cheers!