I Ported Coreboot to the ThinkPad X270
dork.dev251 points by todsacerdoti 16 hours ago
251 points by todsacerdoti 16 hours ago
I wonder if this can help with the extremely irritating bug (intentional?) on the X270 where if you give it a third party 9-cell battery, it will raise CPU_PROCHOT all the damn time, and my processor would drop to below 1Ghz clock speeds.
Back when I used to have an X270 I had a shell script that ran on boot which poked a register to disable thermal throttling handling. Not at all ideal, but it made the machine usable in the absence of official Lenovo batteries which they stopped manufacturing pretty damn quickly.
You can use ThrottleStop[1] to disable PROCHOT on non-standard battery. I encountered similar issue with throttling on my Dell Precision laptop when I was charging it via 60 W USB-C charger instead of proprietary barrel-type 130 W plug. The system triggered a warning about low power charger and initiated aggressive cpu frequency scaling. By using ThrottleStop, I was able to use type-c 60W charger on lightweight tasks (such as web browsing, older games) just fine.
[1]: https://www.techpowerup.com/download/techpowerup-throttlesto...
Dell likes to pull this stunt on other devices too. Like their 1L desktops in the OptiPlex line that I managed for many years. Even though we were using genuine Dell power adapters, if they became slightly unplugged but remained powered, they would enable PROCHOT.
This was fine until the machines randomly started setting PROCHOT on genuine power adapters that were fully plugged in. Eventually I just deployed a configuration with PDQ to all the machines that ran ThrottleStop in the background with a configuration that disabled PROCHOT on login.
Unfortunately, I couldn't get it to consistently disable PROCHOT pre-login, so students and teachers in my labs would consistently wait 3-4 minutes while the machines chugged along at 700 MHz as they prepared their accounts.
On my non Thinkpad lenovo yoga (Whiskey Lake) disabling bd_prochot leads to crash.
I was the happy owner of ThinkPad X1 Extreme g1. It had that bug out of the box, new original battery. Once it thermal throttles, it never goes back to full GHz. It throttled pretty soon, cause big CPU small chassis. Yes, I had a script like that.
It is still somewhere on a shelf, so maybe its day will come again.
Nice to finally know what was happening to my x270 after so many years. Well good thing it doesn't happen when connected to power nowadays is my home server
Yeah, I wrote a similar script. Run it once I see the clock going to 400, but wait for eternity for the sudo prompt emerge before running it.
I wonder now if a similar problem is present in the A285 which is a cousin of the x270
Possibly. Usually this is handled by the embedded controller, and not sure if that was reversed or not. You may be able to tristate the GPIO line that tells the CPU that a pin means PROCHOT, which would allow you to ignore the ECs attempts to do this.
Thinkpads do same thing when detecting 65W supply instead of 90W despite you only need 90W if running full tilt while charging.
Do you think it could also be due to an ACPI table?
Its possible. I know from the BIOS revision changelogs that the T470 did get a patch to fix this, but the X270 never did.
> I can’t recommend libreboot enough, or even heads if libreboot isn’t your speed.
Why though? Not a single reason mentioned in post about why would it be better than whatever stock BIOS the laptop is shipped with.
Some people prefer to know exactly what their computer does, either to enable debugging in obscure cases or due to security concerns.
Thanks to Intel, who has invented the completely unnecessary System Management Mode, to compensate for the laziness of Microsoft, who could not be bothered to update MS-DOS and Windows with some features required in modern computers, now the BIOS has the ability to do whatever it wants on your computer, without this being detectable by the owner.
Hopefully the BIOS writers do not abuse this, and the many problems caused by BIOSes are due to unintentional bugs and not due to malice, but it would still better to be certain that your firmware does not do anything nefarious.
When debugging hardware problems, it is also much simpler when you are certain about what the computer really does, instead of not knowing whether the BIOS takes control when certain hardware events happen, overriding any policies that you may try to implement in your operating system.
Replacing the proprietary BIOS still does not provide complete control over what you own, as there are auxiliary CPUs with their own agenda, but it is still much closer to full control than when you do not know what the BIOS does.
> Hopefully the BIOS writers do not abuse this
Unfortunately, they have. Multiple examples from the excellent Cathode Ray Dude:
https://www.youtube.com/watch?v=q5M0TwnkWUM https://www.youtube.com/watch?v=ssob-7sGVWs
The goal of that blog post is not to sell you something.
This can be confusing on HN, I know.
A recommendation without context is pointless. A recommendation with context could be very helpful!
It replaces a proprietary component of your system with an open source one.
Reading https://libreboot.org/#why-use-libreboot might provide further enlightenment.
That still doesn't answer the question of why it's better. Unless you're paranoid about an OEM backdoor, I think this is cool but not worth the effort.
I think firstly is the FOSS obsession and backdoor paranoia from evangelists, and secondly and the more practical one is that the proprietary IBM BIOS is full of bugs and anti-consumer blacklists and whitelists designed to limit repairability and upgradeability, which stil boggle my mind on how those laptops got such a good image on that front.
I mean, maybe paranoia is the wrong word.. it's not something that I'm personally worried about, but stuff like that has actually happened.
>but stuff like that has actually happened
Yes, if you live and organize your life around things that are unlikely to happen to you, but only because they've happened ONCE to someone else, typically a high value target by state actors, that's called paranoia.
Most people are not gonna be targeted via BIOS hacks. From state actors to online scammers they all have easier ways to getting your data remotely.
> Unless you're paranoid about an OEM backdoor
Lenovo does have a history with installing a very obvious spyware rootkit on their consumer PCs[0].
[0]https://support.lenovo.com/us/en/product_security/ps500035-s...
I think you've pretty much summed it up.
As far as I'm aware, it has less functionality than the OEM, so you use it to _remove_ features (good and/or bad).
Aside from that, I suppose it means you can run a more up to date firmware if yours is no longer maintained, but I'm not sure what that means in practical terms.
There's also the "hyper paranoid" fork "canoeboot" which has no proprietary blobs, and presumably _even less_ functionality.
The short answer is; if you don't know why you want it or need it, you probably don't.
This answer is "do it out of principle". OP is looking for the practical considerations.
As far as I can tell, this is the only reason, you'll likely lose a bunch of functionality (that's been my experience); so "principle" is the only reason I'm aware of (or minimalism, but that's a principle too is it not?).
I suppose if nothing else, you can run a more up to date firmware if the vendor stopped supporting yours, but I have no idea what that means in a practical sense.
Really cool! I wish that Coreboot was available for more recent Thinkpads. I have a Z13 Gen2 which I plan to use until it falls apart, and would love to liberate it with Coreboot. But alas, I can't.
How's your experience with that? It's on the top of my dream laptop list but it's expensive and the second gen is more so....looks like they killed off the line right before it got to the sweet spot (ryzen ai max line) just like the surface laptop which makes me sad.
There were a lot of reports about those things having power or heat firmware problems?
I have one for work; I was excited to receive it, I’ve never been more disappointed with a laptop bearing the ThinkPad brand. Lots of intermittent issues with graphics, BT audio, and performance.
How did OP debug this without a serial port?
I’ve messed around with porting coreboot on two desktop platforms but always had the benefit of a HW serial port…
because the x280 and x270 are similar enough I didn't need to try very hard to get it to post or boot a live USB to further investigate (effectively acting as a decent template for me to work off of)
The console viewing itself was provided by `cbmem -1`, which I could run via a NixOS live USB with nixpkgs#coreboot-utils
You can sometimes find the serial lines if you are careful. Otherwise you can use the flashrom to store the output, and read it back out after each failure. It is much easier to just poke around and find the serial if you can, either from schematics (it seems the author has these) or by hand with a lot of patience or board scrying.
pretty cool work! Though it leaves me wondering if coreboot/bios code can directly interface with thermal-management and battery controller , shouldn't it be feasible to improve upon battery life by exposing some interface to OS, like apple laptops ?
I always wondered, what is the practical advantage of running coreboot on my laptop?
The PROCHOT discussion in this thread is a good example. Lenovo stops making batteries, third party ones trigger artificial throttling, and the only fix is poking registers with a boot script. With coreboot you can just... fix it properly.
More broadly: faster boot times (sub-second POST is common), no vendor bloat or hidden phone-home behavior in the firmware, and you can actually audit what runs before your OS loads. That last one matters more than people think. Your BIOS has full access to everything on the machine before any OS-level security even starts.
This is absurdly trans-coded.
Ah, todsacerdoti. ;)
[flagged]
Seek and thou shalt find. Just don’t be too pushy on the romantic side of things.
Too late for me then I suppose, I'm married with two kids.
This gave me a good chuckle :)
I'm glad you saw it as humor- thats how it was intended. I love my wife dearly but we spend our free time very differently. I'm an engineer, she's an epidemiologist. I'm more creative and like to build things, she's more interested in watching the news. We do have great conversations about cosmology and physics though.
Was AI Used?
Hi! As the author, no! I take a hard line stance against AI use myself. It's just not for me.
Good thing is even if you did use AI, the AI can't do the SMD rework on the laptop ;)
Does it matter?