[Solved] Disabling CMOS Checksum Error on Thinkpad X250

BIOS/UEFI Modding BIOS Modding Requests
1

Hello everyone!

I have a Thinkpad X250 with a modded BIOS including advanced BIOS menu and CFG bit unlocked. It is running macOS Monterey and everything works (almost) perfectly, there is a strange problem with Hibernation which I can’t figure where it comes from.

The thing is when I put the laptop into Hibernation, it shuts down well and resume perfectly when I turn it on again, but on the next boot it throws me this error “0251: System CMOS Checksum bad - Default configuration used”. I’ve litteraly tried everything on macOS/OpenCore side with HibernationFixup, RTCMemoryFixup, by targetting the RTC offsets which shouldn’t be written but it seem that it doesn’t changes anything. The problem is not present with Linux/Windows and macOS when I use Standby S3 sleep.

So my new idea is to see if it is possible to mod the BIOS to disable warnings related to this CMOS error, the UEFI module in question is named “DxeCmosInit”.

Does anyone has any idea how to do this?

Alternatively, do you think it’s possible to just remove the DxeCmosInit module from the BIOS, will it boot/work?

Thanks a lot!

1 Like
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An update to say that the problem is SOLVED!

The fix was easy, I just removed the “DxeCmosInit” module from the UEFI Bios with UEFITool, then flashed back the modded Bios (with CH341A programmer), no more CMOS checksum check/error on boot (winning few seconds).

Regards

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Hi, i’m having the same problem with my thinkpad t14 gen 1, have you experienced some issues after you erase this module? Also, do you have some tutorial to do this process? Thank you in advance.

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Hi Pimpi,

I can try to guide you in this process but I need first to do some research on your ThinkPad model to check if the BIOS is easily flashable.
And you will probably need a CH341A programmer, and be ready to open your laptop and make a dump of your BIOS.
Do you have any experience with this?

Regards

PS: Didn’t experienced anything wrong after removed this module.

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Well… According to here: ThinkPad T14 Gen 1 AMD patches dont work · Issue #48 · digmorepaka/thinkpad-firmware-patches · GitHub
It’s not possible to flash and unlock this laptop model yet.