Shuttle K48 and speedstep.

[Rasmus Wiman <rasmus@wiman.org>]

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Hi everybody,

a few months ago I bought myself a Shuttle K48 to use with Vortexbox as
a media PC. I put in an old Intel Pentium dual-core E2140 that I had
lying around. However, even after getting a better fan I still found it
a bit on the noisy side, so I decided to try a 45ns cpu and got a dual
core E5300. Better, but now speedstep stopped working.

modprobe -v acpi_cpufreq

gives me:

FATAL: Error inserting acpi_cpufreq
(/lib/modules/2.6.30.10-105.fc11.i686.PAE/kernel/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.ko):
No such device

By googling a bit I found the thread "[Help] I can't get Intel
Speedstep working" on this list, started in march by Robert Szalai, who
uses a Core 2 duo E7200, which seems to be essentially the same cpu as
the 5300 but with faster bus speed etc.

Since I still had the E2140 (Speedstep actually works with that CPU), I
put it back in so I could do an acpidump with that cpu and compare the
outputs. It seems to me that an SSDT is there when the E2140 is
installed, and when I substitute the 5300 it goes away. Also, a few
bytes in the RSDT differ. The SSDT definitely looks like it contains
speedstep related stuff even though I know nothing about iasl.

Since speedstep with 45ns processors apparently works in windows, would
it be wrong to assume that windows (or whatever drivers Shuttle provide
for windows) keeps a bunch of extra SSDT:s around and kludges them in
if a 45ns CPU is present?

Both acpidumps are attached and if someone creates some kind of patch
I'll of course try it.

Thanks a lot
Rasmus Wiman


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