Re: constant processor 0x80 events

Faye Pearson [faye-6JSjyQ0Qj1ReoWH0uzbU5w@public.gmane.org] wrote:
(but forgot to cc to the list)

Adachi, Kenichi [aileenja-dTzOdQ2U+/YAvxtiuMwx3w@public.gmane.org] wrote:

quoted

Actually your _PPC first evaluates 8 bits field "THRT" defined in the
"MNVS" OpRegion created in SystemMemory, which likely holds some
information about thermal condition, and if THRT is zero, we go to Else
term, ending up no P-State change. P0 stays as the highest available
P-State. 

THRT = Throttle?  Anyway, nothing in the DSDT updates that field.  Is
the OS supposed to?  Perhaps that is what the OS is supposed to assert
when it receives this message?  I hate groping in the dark :/

I've used THRT as the one shot flag in the meantime and I'll see how it
goes.

quoted

Huum, interesting. You're seeing whole bunch of Notify 0x80 on CPU0, ---
for what reason??? What makes your system to raise GPE and what is the
expected consequence? This is a sort of Hardware/BIOS design issue and
only BIOS writer can tell us everything,,, Do you have any idea?

The only time I've seen this is when the processor has been running at
full pelt for some time - ie the CPU temp is high.  I would say that the
processor is just trying to tell the OS to switch the processor state
down 'cause it's hot.  Probably in the wrong way :)

I would say it's probably wrong to flood the system with these events.

Is the event being sent as quickly as it can be received?  If so then
the action associated with the event should be run from the same thread
or it will never be actioned.

quoted

Anyway typical usage of 0x80 I've seen is to really update P-State table
upon AC plug-in/out, and even in this case, if Notify 0x80 rushes in a
quick succession (due to chattering for example), system may misbehave. 

Perhaps it should be a one shot, reset when the processor state changes?
eg. in _L00

If (LNot(THRT)) {
  Store (One, THRT)
  Notify (\_PR.CPU0, 0x80)
}

and in _PPC

If (THRT) {
  Store (Zero, THRT)
  Return (One)
}

This is what I'm currently running with.  The thing is I'm not sure
whether that will cause any other side effects - any ideas?

quoted

Please let me know your test result and if it doesn't work out, let's
look into code to figure out the best way. It could be bug in OS code
executing GPE Handler or bug in processor driver code handling 0x80
notification or what else...

Well, it does prevent the rush of messages but I don't think that's an
elegant solution.  How do other laptops report overheat request for
Pstate change?

-- 
Faye Pearson,
Covert Development
ClaraNET Ltd.       Tel 020 7903 3000

Eschew obfuscation.


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