[CFT] Sparse Cstate Support -- Its possible, that I don't know
what I'm doing.
Sean Bruno
seanbru at yahoo-inc.com
Wed Jun 20 20:55:58 UTC 2012
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 ... :-)
Sean "I have no idea how computers work" Bruno
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