- The CPU microcodes are under a non-free license that is incompatible with coreboot's license.
- They are now moved away in a separate repository.
Some people say that the microcode is the equivalent of having a more recent CPU, as a justification for using it.
However since Intel microcodes are encrypted and signed, so we cannot know what they really do.
- People usually trust what the CPU vendor say about it, such as that it fixes some bugs(erratas for such bugs are published), but we don't know much more.
- Speculating about what they really do or cannot do won't help much since we usually cannot verify that information.
My goal is to have a 100% free computer, and also to spread that code, so that other people can have a 100% free computer too. According to the FSF, and the FSF criteria for differentiating software from hardware, that microcode is software. So since they consider it as non-free, a coreboot image containing that microcode would not be considered free by the FSF.
On my Lenovo x60, the microcode was easy to remove, and it worked fine, beside printing a scary kernel message pointing to an Intel errata.
What the errata says is that, when resuming from suspend to ram, the temperatures reading will not be updated, and the temperature overheat will not be reported. The hardware issues you may encounter will depend on your specific CPU. Not the CPU model, but instead the date at which it was manufactured. (To know if you are affected, under GNU/Linux, you can run the "dmesg" command and look for "coretemp: Errata AE18 not fixed, update BIOS or microcode of the CPU!" in its output. If you found it, you are affected)
Removing the microcode make it possible to have the gluglug (now minifree) Lenovo Thinkpad X60 ceritified "Respects your freedom" By the FSF.
So instead of debating trough huge flames about the fact that we should use, or not use the microcode, it was more effective to remove it and get the laptop certified.
The benefit of that is the publicity around the fact that this laptop can be made to run 100% free software. This makes users aware of it and willing to switch to it.