Software Functional Overview
FIC A360 Service Manual
3-31
3.5.13
Hardware Thermal Events
An ACPI-compatible OS expects the hardware to generate a thermal event notification
through the use of the SCI. When the OS receives the SCI event, it will run the _TMP control
method to evaluate the current temperature. Then the OS will compare the value to the
cooling policy temperatures. If the temperature has crossed over one of the three policy
thresholds, then the OS will actively or passively cool (or stop cooling) the system, or
shutdown the system entirely.
5
10
15
20
25
30
35
40
45
50
55
60
75
80
85
90
_AC1
_PSV
_CRT
Method
SCI Event
This is an SCI and you
can define how ever
many as necessary
_AC0
Figure 3-3
SCI Events
Both the number of SCI events to be implemented and the granularity of the temperature
separation between each SCI event is OEM-specific. However, it is important to note that
since the OS can use heuristic knowledge to help cool the system, the more events the OS
receives the better understanding it will have of the system thermal characteristic.
3.5.14
Active Cooling Strength
The Active cooling methods (_Ac
x
) in conjunction with active cooling lists (_AL
x
), allows an
OEM to use a device that offers varying degrees of cooling capability or multiple cooling
devices. The _AC
x
method designates the temperature at which the Active cooling is enabled
or disabled (depending upon the direction in which the temperature is changing). The _AL
x
method evaluates to a list of devices that actively cool the zone. For example:
•
If a standard single-speed fan is the Active cooling device, then the policy is
represented by the temperature to which _AC0 evaluates, and the fan is listed in
_AL0.
•
If the zone uses two independently-controlled single-speed fans to regulate the
temperature, then _AC0 will evaluate to the maximum cooling temperature using two
fans, and _AC1 will evaluate to the standard cooling temperature using one fan.
•
If a zone has a single fan with a low speed and a high speed, the _AC0 will evaluate
to the temperature associated with running the fan at high-speed, and _AC1 will
evaluate to the temperature associated with running the fan at low speed. _AL0 and
_AL1 will both point to different device objects associated with the same physical fan,
but control the fan at different speeds.