Advanced Configuration and Power Interface Specification

Processor Configuration and Control
Element
Lowest Performance
Guaranteed
Performance Register
Desired Performance
Register
Minimum
Performance Register
Maximum
Performance Register
Performance
Reduction Tolerance
Register
Integer
(DWORD)
or Buffer
Buffer
Buffer
Buffer
Buffer
Buffer
Indicates the lowest performance level of the processor. If this
element is an Integer, OSPM reads the integer value directly. If this
element is a Buffer, it must contain a Resource Descriptor with a
single Register() to read the value from.
Optional. If supported, contains a resource descriptor with a single
Register() descriptor that describes the register to read the current
guaranteed performance from. See the section “Performance Limiting”
for more details.
Contains a resource descriptor with a single Register() descriptor that
describes the register to write the desired performance level. This
register is optional when OSPM indicates support for CPPC2 in the
platform-wide _OSC capabilities and the Autonomous Selection
Enable register is Integer 1
Optional. If supported, contains a resource descriptor with a single
Register() descriptor that describes the register to write the minimum
allowable performance level to. The value 0 is equivalent to Lowest
Performance (no limit).
Optional. If supported, contains a resource descriptor with a single
Register() descriptor that describes the register to write the maximum
allowable performance level to. All 1s is equivalent to Highest
Performance (no limit).
Optional. If supported, contains a resource descriptor with a single
Register() descriptor that describes the register to write the
performance reduction tolerance.
Time Window Register Buffer Optional. If supported, contains a resource descriptor with a single
Register() descriptor that describes the register to write the nominal
length of time (in ms) between successive reads of the platform’s
delivered performance register. See the section “Time Window
Register” for more details.
Counter Wraparound
Time
Reference
Performance Counter
Register
Delivered
Performance Counter
Register
Performance Limited
Register
Object
Type
Integer
(DWORD)
or Buffer
Buffer
Buffer
Buffer
Description
Optional. If supported, indicates the minimum time to counter
wraparound, in seconds. If this element is an Integer, OSPM reads the
integer value directly. If this element is a Buffer (and supported), it
must contain a Resource Descriptor with a single Register() to read
the value from.
Contains a resource descriptor with a single Register() descriptor that
describes the register to read a counter that accumulates at a rate
proportional the reference performance of the processor.
Contains a resource descriptor with a single Register() descriptor that
describes the register to read a counter that accumulates at a rate
proportional to the delivered performance of the processor.
Contains a resource descriptor with a single Register() descriptor that
describes the register to read to determine if performance was limited.
A nonzero value indicates performance was limited. This register is
sticky, and will remain set until reset or OSPM clears it by writing 0.
See the section “Performance Limiting” for more details.
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