Comments on: Undervolting in Ubuntu 10.04 (Lucid) LTS

By: hanktard

hanktard — Fri, 03 Feb 2012 09:44:15 +0000

In Ubuntu 11.10 i had to add phc-intel to /etc/modules in order to get it to load at boot instead of acpi-cpufreq. to unload acpi-cpufreq on my running system caused an error since the module was in use.

By: JamesRamone

JamesRamone — Fri, 13 Jan 2012 14:33:56 +0000

Thanks alot, that script just made my day I’m on oneiric, I have phc kernel, drivers but I wasn’t able to run phc-tool… Your script just did what I needed
Btw. I have Acer 6920g and default voltage set 200mV higher than the values from Intel is really not cool…
Once more, thank You

By: siem

siem — Tue, 20 Dec 2011 07:06:06 +0000

How long shoult I wait after ‘make prepare’? It seems nothing is happening and I’m waiting since five minutes or more…

By: Scott

Scott — Tue, 29 Nov 2011 16:26:32 +0000

This is what I get:
scott@scott-laptop:~/Desktop/phc-intel-0.3.2-10$ uname -r
2.6.32-33-generic-phc
scott@scott-laptop:~/Desktop/phc-intel-0.3.2-10$ make prepare
FOUND AVAILABLE PATCHSET. PREPARING.
patching file phc-intel.c
scott@scott-laptop:~/Desktop/phc-intel-0.3.2-10$ make
make -C /lib/modules/`uname -r`/build SUBDIRS=/home/scott/Desktop/phc-intel-0.3.2-10 modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.32-33-generic-phc’
CC [M] /home/scott/Desktop/phc-intel-0.3.2-10/phc-intel.o
Building modules, stage 2.
MODPOST 1 modules
LD [M] /home/scott/Desktop/phc-intel-0.3.2-10/phc-intel.ko
make[1]: Leaving directory `/usr/src/linux-headers-2.6.32-33-generic-phc’
scott@scott-laptop:~/Desktop/phc-intel-0.3.2-10$ sudo make install
install -m 644 -o root -g root phc-intel.modprobe /etc/modprobe.d/phc-intel.conf
mkdir -p /lib/modules/2.6.32-33-generic-phc/extra
install -m 644 -o root -g root phc-intel.ko /lib/modules/2.6.32-33-generic-phc/extra/
depmod 2.6.32-33-generic-phc -a
scott@scott-laptop:~/Desktop/phc-intel-0.3.2-10$ cat /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids
cat: /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids: No such file or directory

I have rebooted a couple times already and am not sure where to go from here. I did navigate to /sys/devices/system/cpu/ and instead of cpufreq being a subfolder of cpu0 it is in the same folder. I think this may be causing this but if I look in cpufreq there is not phc_default_vids. Any suggestions?

By: Benko

Benko — Sun, 02 Oct 2011 19:36:55 +0000

I have a laptop with a Core 2 Duo P8xxx. I run W7 and Ubuntu 10.04 (both 64-bit) on it.

I use RMClock on my W7 partition and I know that my system runs fine under full load at 0.925V (I have been running it for more than 30 months now).

Is there any way I can painlessly undervolt the CPU on Ubuntu without going through the long testing steps? If not, I may just have to suck it up and follow the above instructions.

Thank you, this is a great guide.

By: bigley

bigley — Fri, 26 Aug 2011 00:39:08 +0000

Everyone, do an update. noticed that there is a new PHC kernel 2.6.32-33 out for us lucid user. Many thanks for the update

By: Sebastian

Sebastian — Sat, 13 Aug 2011 00:21:56 +0000

thx, but 22 20 20 17 worked fine. Problem was the script always counted down to 0 for all 4 values.
Now I installed Ubuntu 11 and the installation of phc doesn’t work When I run sudo make, terminal returns:
make[2]: *** No rule to make target `kernel/bounds.c’, needed by `kernel/bounds.s’. Stop.
make[1]: *** [prepare0] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.38-8-generic-phc’
make: *** [phc-intel.ko] Error 2

By: bigley

bigley — Thu, 04 Aug 2011 04:57:04 +0000

Sebastian, to be on the safe side I would put in the higer values of the two sets of tests.
For me I was lucky, that everytime I ran the script it resulted in the same values.

I would probably try in your case 39 28 23 17 in the rc.local.

You will find out if these values don’t work when your PC suddenly becomes unstable for no apparent reason. Good luck

By: Sebastian

Sebastian — Tue, 02 Aug 2011 00:41:41 +0000

My Values: 39 28 23 17

Ok, there is something I odn’t understand. When I run your script it goes down from 39 to 0. Then I restart your script and it gows down from 39 0 23 17. Then I restart your script and it goes down from 39 28 0 17, etc.

So what exactly I got to add in /etc/rc.local then?

By: Alexandria Medina

Alexandria Medina — Thu, 28 Jul 2011 11:29:12 +0000

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