[ltp] how to determine the true c state?

[Robert Tomsick]

On Sun, 2009-11-22 at 23:53 +0100, Matthias Rieber wrote:

> I've switched from Ubuntu 8.10 to 9.10. In 8.10 powertop reported C6 as 
> lowest state (in non-AC mode). After upgrading to Ubuntu 9.10 it only 
> shows C4 in powertop.  Unfortunately there was a bios update in between, 
> so I don't know if this was caused by the kernel or bios update or any 
> other chage during the distribution update.

Just a quick question: are you taking these readings on AC or on battery
power?

I know that on my X200s powertop only reports C4 as the lowest sleep
state when the machine is plugged in.  When it is on battery power,
however, the lowest listed state is C6.  I suspect that the BIOS is only
exposing C6 when on battery power.

The X200s is definitely a different machine than the X301, but mine has
an SU9300 in it, so it's a similar chip to the one inside your X301
(SU9400 or SU9600) -- this might just be how the ULV-based X200/X30x
series machines behave.

-Rob