The more I learn about the VIA C3, C7, and EDEN cpu chips, the more I like them. I’ve been trying to figure out more about how to get acpi processor frequency scaling with them. Here’s been my experience so far. C3

I’ve heard that the longhaul driver works for the ASUS Terminator C3. Unfortunately I just tried it and it didn’t work:

insmod /lib/modules/2.6.15-28-386/kernel/arch/i386/kernel/cpu/cpufreq/longrun.ko

insmod: error inserting '.../longrun.ko': -1 No such device

Duh. I just spent the afternoon compiling longhaul, but then try to insmod longrun. I just insmodded longhaul and it works! :-) Unfortunately, when the processor is at its lowest frequency (400Mhz) I get this high pitched whine coming from the computer. I just installed powertweak to see if I can omit that cpu frequency from the cpu frequency adjusting daemon. If that doesn’t work, I’ll try to modify the scaling_available_frequencies file (though I’ll probably have to do that every restart?). Powertweakd is a lot more than I need to simply alter the available frequencies. I’m instead using the cpufrequtils file in /etc/default to raise the minimum frequency to 532000 so that the cpu won’t emit that annoying high pitched whine. C7

There is some new code for the C7 in the testing linux kernel, but for me, the acpi-cpufreq driver worked on my Everex NC1500 notebook. I think the C7 version is actually “e_powersaver.ko”. Hmmm, doesn’t seem like that one is supported by the C7-D. Grrr.

No frequency scaling for C7?

Supposed longhaul driver fix for C7

GMANE message about 65Mhz VIA bug

acpi-cpufreq reports 65mhz

acpi-cpufreq reports wrong frequency bug report at bugzilla

Freq scaling possible through p-states?

VIA C7 Uses ACPI P-States to vary frequecncy

Now I’m trying to install gutsy gibbons, see if that helps any. For what its worth, here’s a screenshot of the PC Chips motherboard BIOS:

I guess the kernel just isn’t quite ready for the C7. From the stuff I’ve found, it looks like there are three potential candidates for cpufreq drivers for the C7:

  • acpi-cpufreq (hasn't worked for me) read reports it would work
  • longhaul - again, didn't work for me, got an error saying C3 Esther doesn't support frequency scaling. ???
  • e_powersave - read somewhere that this won't work with the C7-D


I have a few C7 EDEN chips to try this out on, but haven’t yet: VIA EPIA EN 12000EG Linux kernel compile on Ubuntu. I installed debian on my Eden machines, not ubuntu, but the two are so similar I hope the directions with work for both.