Hi,
I also don't have C-states on my DG965RY intel board with core 2 duo E6400
Any board can support C-states ether by fixed ACPI set of registers or by a
set of functions in acpi tables.
On my system ICH8 (and I almost sure you got it too), doesn't support
fixed-function C-states.
And there is no other magic chip that can put cpu in c-state (on my system) ,
so acpi has no "set of functions to do that"
So I guess that on my board there is no physical support for C-states, and
this could be true for you too.
Anyway monitor/mwait can put cpu in C1, and having apic-stops-in-c2/c3 bug,
I don't think those states are that needed.
The Speedstep support is a different thing at all:
Agian acpi has a function that can change cpu clock speed to fixed values,
And yes on my board it also has only two values: 1500 and 2130.
This support is implemented by accessing the clock chip
(Actualy on my system acpi writes a magic value to one of ICH8 registers, and
this triggers a SMM that changes the clock)
And the last thing is about throtting states your and mine system does
support:
Throttling states are states that make system halt cpu for some % of time,
Yes there are 8 such states. You can enter one of those by writeing a state
number to /proc/acpi/processor/*/throttling (I assume you have ICH8 or
someting simular)
Also ICH*'s throtting states are system global, this is why I wrote "/*/"
If you change it for one core, it will be changed for other.
They are supported by fixed acpi function (by ICH8)
My 2 cents.
Regards
Maxim Levitsky
-