Fighting for the power.

Hans Petter Selasky hselasky at
Mon May 4 07:24:06 UTC 2009

> 2. PCI devices
> PCI bus provides method to control device power. For example, I have
> completely no use for my FireWire controller and most of time - EHCI USB
> controller. Disabling them allows me to save about 3W of power. To
> disable all unneeded PCI devices you should build kernel without their
> drivers and add to loader.conf:
> hw.pci.do_power_nodriver=3
> To enable devices back all you need to do is just load their drivers as
> modules.

The new USB stack should turn off USB HC's automatically when not in use. At 
least the schedules will get disabled. Did you do any research on this?


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