CPU C-state storange on Panasonic TOUGH BOOK CF-R9

[Alexander Motin]

Andriy Gapon wrote:
> on 14/09/2010 11:44 Andriy Gapon said the following:
>> on 13/09/2010 20:07 Andriy Gapon said the following:
>>> I am also going to take a look how Linux and OpenSolaris name the C-states.
>> Well, Linux does what you suggested, it uses index of a C-state as its name.
>> There is one difference from our current code - if a C-state is skipped for some
>> reason, then its index is not re-used, but the entry is marked as non-valid.
>> So, if we skip "C2" for some reason, then "C3" will become "C2".  Not so on Linux.
>> Also, they print a type/class of a C state using C1, C2, C3 and "--" for
>> higher/unknown types.
> 
> OpenSolaris, on the other hand, collapses multiple entries of the same type into
> a single entry using the most power-saving alternative.

I don't think it is perfect choice. In such case it would be useless for
ACPI BIOS to report extra states. The only case when I think can be
reasonable to drop some items is if they are equal except using
different entry methods. For example, one OS may prefer to use port
read, while another may use MWAIT to be able to wake up without using IPI.

> They also use the type as a C state reported name, index is not used in interfacing.

In their case it is possible.

-- 
Alexander Motin