I Ported Coreboot to the ThinkPad X270(dork.dev)
163 pointsby todsacerdoti8 hours ago8 comments
  • amiga-workbench6 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.

    • gritzko3 minutes ago
      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.

    • muniter4 hours ago
      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
    • inamberclad3 hours ago
      Oh almost certainly. PROCHOT is programmable.
    • 65a5 hours ago
      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.
    • rasz3 hours ago
      Thinkpads do same thing when detecting 65W supply instead of 90W despite you only need 90W if running full tilt while charging.
    • nxobject5 hours ago
      Do you think it could also be due to an ACPI table?
      • amiga-workbench5 hours ago
        Its possible. I know from the BIOS revision changelogs that the T470 did get a patch to fix this, but the X270 never did.
  • BobbyTables25 hours ago
    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…

    • katdork4 hours ago
      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

    • 65a5 hours ago
      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.
  • warangalan hour ago
    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 ?
  • 2 hours ago
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  • reductum5 hours ago
    Atom feed is malformed :(
    • katdork4 hours ago
      sorry, I'll look into it
  • mattv86 hours ago
    What I would give for a wife that would enjoy tinkering with me.
    • notpushkin5 hours ago
      Seek and thou shalt find. Just don’t be too pushy on the romantic side of things.
      • mattv85 hours ago
        Too late for me then I suppose, I'm married with two kids.
        • esseph2 hours ago
          This gave me a good chuckle :)
  • brcmthrowaway6 hours ago
    Was AI Used?
    • katdork4 hours ago
      Hi! As the author, no! I take a hard line stance against AI use myself. It's just not for me.
    • wetpaws6 hours ago
      Does it matter?
      • uhfraid2 hours ago
        on HN in 2026, I’d say it’s never mattered more lol
        • vips7L2 hours ago
          HN? You mean Molt News?
      • fragmede5 hours ago
        [flagged]
  • periodjet5 hours ago
    This is absurdly trans-coded.

    Ah, todsacerdoti. ;)

    • katdork4 hours ago
      I am a trans woman, yes :o

      (the user who posted my blog post is not me :p)