I noticed that in the 3.4.x kernels, the PHC patches are applied to be able to undervolt my notebook cpu (core2duo).
In the newer kernel (I tested 3.9.11) the PHC patch doesn't work for me. Is it removed?
I would love to have that functionality back in the newer kernels. Thanks!
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I checked the linux-phc forums, and the speedstep phc patches have not been updated since 2.6.36, www.linux-phc.org/forum/viewtopic.php?f=13&t=38. In fact, the cpufreq driver they patch is speedstep-centrino, which I believe is already deprecated or less priority than the acpi-cpufreq and intel-pstate cpufreq drivers.

There is a patch for amd's k8 cpus, but the number of people running amd cpus on their laptops is a drop in the bucket to the intel core laptops out there. It's not worth the possibility of instability unless enough people want to manually undervolt their k8 cpus.
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Thanks for checking. I did a double check and it seems to be correct. Too bad actually since PHC seems to be the only "tool" for undervolting cpu's in linux.
I'll stick with an older kernel for now. Thanks
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Hello,

You can get the current version of phc-intel (based on acpi-cpufreq) from www.linux-phc.org/forum/viewtopic.php?f=7&t=267 It is a maintanance pack to accommodate for newer kernel versions. While processors > core2duo are not suported, because they lack the software-tweakability to do so, core duo and core2duo will work fine. At least my notebook runs much cooler with phc-intel and kernel 3.13. If you have problems with this patchset, please drop a message in the phc-forum.

lio
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lio, by default, do the phc patches make changes to reduce voltage without any user intervention, or do you have to tweak it yourself? It would be nice if these developers or users in the community found better defaults that work for 99% of the core and core2 cpus.

EDIT: Also, the 3.12 patch doesn't seem current after 3.12.3 - I'll include this patch set for 3.13.
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The patch does not apply any change by default, because you can't apply a sane default. Even same processor variants can differ heavily in their undervolting ability so it is best left to the users to crash their systems or find crazy computational errors by chance. ;) If you apply the phc-patch and don't tweak a thing its like using stock acpi-cpufreq.

Patches are build against vanilla kernel acpi-cpufreq.c, which is also shipped in the package. For 3.12 the shipped patch applies clean and as vanilla acpi-cpufreq was not modified upstream during 3.12.x lifecycle, I can't find a reason it shouldn't apply for 3.12.3. Do you use a otherwise modified acpi-cpufreq.c?
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