Re: em64t speedstep technology not supported in kernel yet?
From: Wes Felter
Date: Thu Sep 29 2005 - 14:05:55 EST
Richard Wohlstadter wrote:
Hello all,
We recently had Intel give our company a roadmap presentation where they
told us that their enhanced speedstep technology was supported by linux
kernels 2.6.9+. I have since tried to get cpufreq speedstep driver to
work with no luck on our em64t Xeon 3.6g processors. Intel even has a
webpage describing the technology and how to get it working at url:
http://www.intel.com/cd/ids/developer/asmo-na/eng/195910.htm?prn=Y
I think this is a BIOS problem; the BIOS needs to provide the proper
ACPI frequency/voltage tables for cpufreq to use. You might want to
harass your system/motherboard vendor.
Alternately maybe you can find someone who can give you the secret table
and then you can just hardcode it into the driver.
The only processor I have had luck with so far is a 32-bit Xeon with the
p4-clockmod driver(which does not appear to be present in the x86-64
kernel).
Beware that p4-clockmod won't increase the power efficiency of your
system. (As an aside, clock modulation is so simple that you can do it
from userspace in a few lines of C if you modprobe msr. This works on
x86-64.)
Wes Felter - wesley@xxxxxxxxxx
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