X230 Power Consumption with Coreboot

[katzinator]

I've come across various conflicting opinions regarding power consumption and/or battery performance with Coreboot. Can anyone comment or provide insight as to whether or not Coreboot impacts battery life? If so, to what degree and why?

I've asked this same question on /r/thinkpad and still wasn't able to reach a firm conclusion. Ideally, I'd like to hear from someone who has personally compared performance of Coreboot with the original Thinkpad BIOS.

[w0qj]

Hey katzinator,

Welcome to the ThinkPads forum!

Wow, you have a very product specific question, not sure if anyone else has the experience in this...

Admin strike: ***But our understanding is that non-OEM BIOS discussions are prohibited on this forum unfortunately...
We do however NOT allow supervisor password removal discussions.

On the bright side, you may talk about almost anything else around here!

[plus]

Hi katzinator!

I flashed coreboot and applied me_cleaner at the same time, both possibly have an impact on power consumption.
Measured at the wall plug without battery attached, but on-battery mode engaged for testing, my X230 now idles between 9.7 W and 15.2 W while typing.
Sensors, fancontrol and tlp needed adjustments. /sys/class/power_supply/BAT0/power_now has vanished.
The same system drew 2-3 W less before.

Possible reasons, some specific to my setup:
* First of all me_cleaner. Some of ME's functions were saving power.
* DDR3L @1866 memory. A fresh build would initialize at 1.5V @1600 MHz or drop bank1 at all. Not yet there.
* ACPI tables changed, some of the changes still need finer tuning.
* Some predefined strings used by drivers are not in place.
* GRUB2 payload directly boots Linux, maybe some legacy BIOS calls are missing?

So battery performance went down a bit on mine, less than by 20 % on everyday usage.

[ThinkRob]

* First of all me_cleaner. Some of ME's functions were saving power.

I don't think that's the case. IIRC once the ME is out of BUP, it's not doing anything that should affect the power consumption.

Did you neuter it by setting the HAP bit, or did you just remove modules?

[plus]

Did you neuter it by setting the HAP bit, or did you just remove modules?

Both. Only FTPR with HAP bit set, ROMP, BUP and RSA signature are left. ME size is now down to 98kB, mostly 0xFF.
lspci still shows MEI, but it can be hidden via `echo 1 >/sys/bus/pci/devices/0000:00:16.0/remove`.

[ThinkRob]

lspci still shows MEI, but it can be hidden via `echo 1 >/sys/bus/pci/devices/0000:00:16.0/remove`.

IIRC the MEI controller will always show up. It's just that you can't actually talk to the ME once neutered.

After BUP, the ME should be basically sitting there crashed.

Now regarding power consumption, I think what might happen with coreboot is that the hardware init is different from the stock BIOS, and so there are probably some hitherto-unknown "magic pokes" for maximum efficiency that coreboot is missing. Not sure how one would go about figuring that out, short of some *really* good logic debugging gear.

* GRUB2 payload directly boots Linux, maybe some legacy BIOS calls are missing?

I doubt it's this. I'm running coreboot + SeaBIOS, and I'm about 1-1.5W over stock on identical HW.