Power off for PCI devices

Johannes Hofmann johannes.hofmann at gmx.de
Wed Sep 10 13:51:01 PDT 2008

Hasso Tepper <hasso at estpak.ee> wrote:
> Johannes Hofmann wrote:
>> Nice! Do the modules have to be loaded (and then unloaded) for this to
>> take effect or is it enough to just not load them in the first place?
> It was enough to just not load them even before this patch. Powering down 
> not used devices at boot time was already there with this commit:
> http://leaf.dragonflybsd.org/mailarchive/commits/2008-09/msg00051.html
> This patch adds just the ability to power down a devices on module unload.

Ah ok. Is there a way to verify the state of the pci devices?
On my T42 thinkpad I don't see any difference in power consumption
with hw.pci.do_power_nodriver=1 (measured with an external device and
battery removed). I'm always around 20 Watt, with est enabled,
"DynamicClocks" "on" in xorg.conf, and screen backlight set to the
lowest possible value.


More information about the Submit mailing list