[ltp] Re: Thinkpad T60 Wireless LED on Ubuntu 8.10 (Intrepid Ibex)

[Stefan Monnier]

> Unassociated means you don't have an IP but the antenna is still
> sucking power (maybe not full power, depending on the power saving
> controls, but power all the less). If you have network manager or wicd
> they still scan periodically even when not associated so you antenna
> is transmitting every 2 seconds or so.

Yes, I understand that.  But these are technical details that don't
directly affect me.

>> As mentioned, I don't actually care about the antenna's status, as long as:
>> - it doesn't suck up my battery.

> If I understood your description correctly, the iwl4965 behaviour
> tells you if the antenna is sucking power (the transceiver is on),
> with iwl3965 or what was it, it tells you if you are associated, but
> even if you are not associated then antenna is still on = sucking
> power. People can't hack in but you are paying the power penalty.

I don't see any measurable difference in powertop between not-associated
and rfkilled with my iwl3945 (I'm always using powersaving settings).
So, the power penalty is nonexistent (as it should).  Maybe the fact
that I do not run network-manager (nor wicd or anything like that) makes
a difference.

>> - nobody can hack into my system or capture valuable data.
>> I guess having the antenna really off is good to make sure nobody can
>> detect my presence, but I don't care that much about it, and when that's
>> really needed, the rfkill does that job better than any LED can.
> The led is an indication to the rfkill state. Led off == rfkill enabled ==
> at least some power waste.

I don't know what machine you're talking about, but the T60 (subject of
this thread) has a physical rfkill switch, and although it's not a led,
it's easy to see its state, so I don't need the wifi led to repeat what
that switch can tell me.

> With my atheros I see a different of about 0.5W between not associated
> (but rfkill disabled) and removing the module (the equivalent of using
> rfkill which doesn't work with my atheros).

With iwl3945 (and ipw3945 before as well), I still get the lowest power
consumption even when I'm associated.


        Stefan