TL;DR: On the xx30 series, the 4MB “top” chip is easily recoverable, even if you fail to make a backup. If you install the 1vyrain BIOS or use 1vyrain to install Coreboot, only the 4MB chip is affected. However, if you apply me_cleaner to the 8MB “bottom” chip and lose the backup, you cannot return to the stock BIOS!

A few years ago, I had wanted to try out Coreboot (using pre-built “Skulls” images), but didn’t want to bother with buying and learning how to use a hardware chip programmer. So I used 1vyrain, as mentioned here: https://lemmy.ml/post/23117122

1vyrain just overwrites the 4MB chip with the supplied image. The 8MB chip is unaffected. Nothing on the 4MB chip is machine-specific. So if you can still boot into Linux but no longer want Coreboot, the recovery is trivial:

  1. Boot Linux with the kernel parameter iomem=relaxed
  2. Install flashrom if needed
  3. Get a copy of the stock 4MB image (I’d recommend v2.60): https://github.com/xy-tech/x330-bios/tree/main/stock/original
  4. Flash the image: sudo flashrom -p internal -i bios --ifd -w /path/to/v2.60.bin --noverify-all
  5. Wait for it to finish and reboot

If it doesn’t POST, you can do the same, but with a hardware programmer.

If you made a mistake with your Coreboot config, but can still boot, and just want to flash a new build of Coreboot, no need to restore stock BIOS and do 1vyrain again, just flash your coreboot.rom like so: sudo flashrom -p internal -i bios --ifd -w path/to/coreboot.rom --noverify-all

That’s all that is relevant if you don’t have a hardware programmer like the CH341a.

Now the mistake that made me write this post: I had extracted the bottom 8MB chip from one of my X230 and applied me_cleaner to it. Seeing it had worked so well, I jumped to the conclusion that a backup for one X230 would work for another X230. So I flashed my second X230 with the cleaned 8MB image without making a backup. Coreboot worked fine, but then I realized I forgot to apply the keyboard EC patch.

Turns out, the contents of the bottom chip are machine-specific and the stock BIOS will not boot if it has been tampered with or swapped with a backup from another machine. And without the stock BIOS, the EC cannot be flashed.

If I do find a way to make the stock BIOS boot again, I will post an update here.