[CFT] Sparse Cstate Support -- Its possible, that I don't know what I'm doing.

[Andriy Gapon]

on 20/06/2012 23:54 Sean Bruno said the following:
> On Wed, 2012-06-20 at 13:18 -0700, Andriy Gapon wrote:
>>> I also, disagree with the idea of "FreeBSD C-states" as that is not
>> the
>>> intention of the code.  The code, from my read, is trying to
>> interpret
>>> C-states as though they are always defined sequentially and
>> non-sparse.
>>
>> I seem to recall that this is an ACPI requirement.  I could be
>> mistaken, but no
>> time to double-check at the moment.
>>
>>
> 
> Just to check as I'm actively looking at this code I went and grabbed
> the December 6, 2011 ACPI spec.  http://www.acpi.info/spec.htm
> 
> chap 8.1 pretty clearly states that C2 and C3 are optional states. So it
> appears that you can have a C3 without a C2.  So, I suspect that the
> idea that the index the cx_states array is always going to be 1 less
> that the ACPI Cstate value isn't by spec.  Or something ...  :-)

I think that the chapter on _CST is more relevant here (8.4.2.1 in my copy of
the spec).  But anyway, there is no such requirement in the specification.  I
was misremembering the requirement that states should be ordered.

So, would you like to produce a cleaned up version of your patch with only this
change in it?

-- 
Andriy Gapon