Fighting for the power.

Paul B. Mahol onemda at
Mon May 4 09:40:43 UTC 2009

On 5/4/09, Alexander Motin <mav at> wrote:
> 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.

Unloading modules doesnt put them back into into D3 state.
You are forced to load some another module again to put wanted device
into D3 state.


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