User:TheSame/nokia-n900 notes/Overclocking on pmOS

Introduction
This manual was created based on a similar manual for Maemo Leste and adapted by the pmOS feature.

After this procedure there will be two kernel images in  partition: normal and overclocked. If you want, you can always return to the normal kernel.

The emmc of my N900 has Maemo Fremantle installed with u-boot installed. This manual is adapted to this situation.

All manipulations, except those related to setting up u-boot, can be done directly in pmOS.

This overclock allows you to use a frequency range of 250Mhz to 850Mhz.

The setup process in Maemo Fremantle
In this step we will create a boot entry for u-boot in Maemo Fremantle.

Creating a boot record for u-boot
1. Create a new entry for u-boot:

2. Run  to add a new entry.

The setup process in pmOS
At this point, we modify the existing kernel and add a new system startup script.

The following commands will create some files. I will create them on the  path, but you can put them wherever you want. All commands below will be done as root.

Creating a file
1. Create a  text file the way you want:

2. Create  file and put it in  :

Creating a modified kernel
1. Get :

2. Get  file. When you run this command you will see a lot of messages, you can ignore them. You may need to install dependencies dtc:

3. Modify  and add new frequencies. To do this, find the  section and edit it according to the example below:

4. Generating a new  file:

5. Create a :

6. Create and put in  a new  :

Checking the success of the operation
After completing all the steps, reboot pmOS using the new item in the u-boot that we added.

You can use cpufrequtils to check if new frequencies have been added. The result should be about the same as below.

If everything is correct, the operation is successful!

You can change the mode of the core for more powersafe:

More fine-tuning of core frequency and voltages
You can try to raise the core frequency above 850 MHz by editing the  to your liking. It all depends on how lucky you are with your SoC. The voltage and frequency can be edited to get the desired result.

To increase the core frequency, edit the variable  according to your wishes. The values must be in HEX format. Example:  = 850000000.

To increase the core volts, edit all 3 numbers in the  variable to your liking. The values must be in HEX format. Example:  = 1350000.

On my device I was able to raise the frequency to 890Mhz without raising the voltage. When I raised the voltage above 1.37V, I lost stability of the system. The system also lost stability when I raised the frequency to 900MHz. According to the information I found, no one has raised the voltage above 1.5V (in Maemo Fremantle).

My final configuration for  (I repeat, it may not work for you):

Useful Links
- A superficial description of the  syntax;

- Maemo Overclocking wiki page;

- A helpful note about maximum voltage;