Hacking task: Driver for ACPI Collaborative Processor Performance Control CPPC appeared since ACPI 5.0 (section 8.4.5). It is available on certain laptops, e.g. Dell e5450. You could use following commands to check it's availability:
mkdir ~/acpitables cd ~/acpitables acpidump -b iasl *.dat grep "\<_CPC\>" *.dsl If the grep gives some output, then CPPC is available. CPPC is the successor of ACPI P-state. It no longer use CPU frequency to control power consumption, instead a set of performance requirement is passed to 'platform', so that 'platform' could adjust various stuffs to meet the performance requirement, e.g. change CPU frequence and memory working mode etc. You could use ACPI P-state driver as start point: /usr/src/sys/dev/acpica/acpi_cpu_pstate.c Thanks, sephe -- Tomorrow Will Never Die
