RE: [PATCH] 1/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Pallipadi, Venkatesh]

> -----Original Message-----
> From: Ducrot Bruno [mailto:ducrot@xxxxxxxxxxxx] 
> Sent: Tuesday, October 21, 2003 10:56 AM
> 
> > It will work any processor 
> > that is ACPI compatible and again there are no specific 
> > checks for Intel here.
> > 
> 
> On a K7 with powernow for example, perf_ctrl and perf_data 
> will be MSR 0
> with your patch, that do not make sence.
> Even if you know the correct MSRs, the values for 'control' 
> and 'status'
> in _PSS packages will be only bit-fields, and they can *not* be
> written nor read directly to the (correct) MSRs (again for K7 
> powernow).
> 
> This is because the FfixedHW is only an indication that a CPU specific
> 'feature' (even though already somehow defined in ACPI like P-state,
> C-state, etc.) have to be handled by the OS in a non-acpi driver, as
> per ACPI spec, and that will be dependant of the CPU.
> 

Agree with most of your comments. 
Current ACPI P-state driver ignored everything other than SYSTEM_IO.
And we are trying to add support for FIXED_HW. I was unaware of
any other CPU using ACPI PCT FIXED_HW to mean anything other than
MSR. As you mentioned, if K7 indeed exports some ACPI-PCT information 
to mean something else, then that is a real bug in my patch. I will 
add CPU specific abstraction to handle FIXED_HW get/set functions in 
the next revision of the patch. 

Thanks,
-Venkatesh
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