VoodooPower Manual

VoodooPower 1.2 User Manual © 2008-09 Superhai Revision 1.2 08-Mar-09 Introduction This is a suite of a kernel extension and a command line tool, which purpose is to provide some power controlling features for the CPU. Most important is the power-step functionality, to lower power footprint. It makes your CPU cooler and/or your battery last longer. For the time being support is for Enhanced Intel Speedstep and experimental AMD Cool'n'Quiet 1+2.

Support If you need help you should go to the support forum found at http://www.superhai.com/ . Link to bug and issue reports are also found there. Source code are available from google code. This is released under "BSD style" license.

Open Source License Copyright © 2008-09, Superhai All rights reserved.

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Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

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USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Installation and running kernel extension Unpack the distribution. You need super user or root access to install kernel extensions. For first use I recommend you first run it from a temporary folder. When you found it to work you may copy it to /System/ Library/Extensions to autoload at startup. To grant kernel access to the kernel extension you can use the following commands. chmod -R 755 /path/to/VoodooPower.kext chown -R root:wheel /path/to/VoodooPower.kext If you copied it into the system kernel extension folder, you will also need to invalidate the kernel extension caches. touch /System/Library/Extension If running from a custom folder use kextload to load the extension kextload /path/to/VoodooPower.kext and to unload it kextunload /path/to/VoodooPower.kext To get super user access use sudo before running these commands. sudo -s Remember! This is a powerful command, so be sure to know what you are doing.

Installation and running of the command line tool No special access is required. You can copy it to a suitable place and remember to grant it access to execute. Run it without options to get the usage. Remember the kernel extension is fully automatic, so this is not required for its use.

Customizing the kernel extension There are a few options to control the kernel extensions behavior. For this you need super user access, as you need to modify the Info.plist inside the kernel extension. You need to find your favorite text or xml editor (it is an xml file). If you use "TextEdit" it will normally not start in correct access mode. You should refer to your OS X documentation to use it with right access. The nodes to change are under PowerControl node in the file, and here is the reference to each.

AutoPowerManager True/False - Choose if you want kernel extension to automatically start the power management straight after loading.

LoopTimerFactor Numeric - This decides how often it updates, check load, probes and manage the CPU. This value can be from 2 to 6 (40 to 640 ms). In debug version it is preset to 9 and can't be changed.

UseEfiFsb True/False - Use FSB value calculated in EFI or SMBIOS/kernel default.

UserVoltageMax/UserVoltageMin Numeric - Needs VoltageOverride to be true. You can use these to customize the voltages, outside or inside the CPU specified limits. Use this if you want to try to under-volt. Although it will not damage the CPU to lower voltage, it may make the system unstable. I do not recommend setting the voltage higher than specified. Use only if you know what you are doing. Behavior of the CPU/system outside of limits are undefined and can result in all sorts of weird errors. The CPU may also refuse to change. The values are in millivolts and have a range from a minimum lower limit specified by the CPU, on Intel core CPU's that is from 712,5 or 825 mV. You can only use integer numbers.

VoltageOverride True/False - See also UserVoltageMax/UserVoltageMin. Override the default voltage table created by the kernel extension. Use with care.

VoltageProbe True/False - Probe for voltage values not specified by the CPU registers.

May cause voltage out of specs or system instability.

OnAC/OnBattery /OnBatteryLow Dictionary - These are profiles for ho the power manager should react in given power modes. The values found under the profile settings are: Threshold Numeric - The load minus/plus hysteresis at which point the powerstepping will trigger. Value is in promille, and 0 is idle and 1000 is full load. Higher values for more aggressive power saving, more responsive CPU use lower values. The available range depends on hysteresis, but with 0 hysteresis it is from 200 to 800 promille.

Hysteresis Numeric - To avoid frequent changes when load is at the trigger threshold it is advisable to have some hysteresis, which is a value added

to or subtracted from the threshold. I.e. you have a threshold of 500 and hysteresis of 25, the trigger to higher P-State will be 525 and for lower 475. Value range is dependent on Threshold.

PStateLimitHigh Numeric - Limit stepping to higher P-States. 0 = no limits and, 1 = max P-State = 1, 2 = max P-State = 2 etc. Remember the most powerful PState is number 0. To force lowest P-State use 32. Should be coordinated with PStateLimitLow. PStateLimitLow Numeric - Limit the lowest P-States. 0 = no limiting, 1 = do not use lowest P-State, 2 = do not use secong lowest, etc. Use 32 to set always highest P-State. Coordinate with PStateLimitHigh.

TStateControl True/False - Enable or disable the stop clock or soft modulation throttle.

T-States are used to slow down the clock while in lowest P-State. The CPU may also use T-States while in critical temperature states before shutting down itself. Recommended mostly for older CPU's or CPU's without powerstep functionality.