[coreboot] ThinkPad X230 with working truncated ME and 11 MB space for payload

[Marek Behun]

> I would try the following to narrow it down: Run the memory training
> with the original ME firmware; keep the MRC cache intact while
> switching to the truncated ME firmware; boot. If it doesn't work with
> the cached values, something around the memory clock might be off. If
> you have de- bug access, you could also directly compare the training
> results from a boot with the original ME firmware vs. the modded
> firmware. If not you can still compare the results from MRC-cache
> dumps. But you'd have to decode them first...

So I tried to put mrc.cache generated with ME into CBFS, but after
reboot, mrc cache was regenerated. I investigated, and found out:
  1) in mrc.cache with ME, the data begins 4 bytes sooner than in
     mrc.cache without ME. This could be the reason why mrc.cache was
     regenerated: the one that was found there (generated by coreboot
     with ME) was invalid for coreboot without ME?
  2) there are different timings in the cache generated without ME.
     I have written an utility to print the data stored there. I am
     attaching those two together with a diff.

I am going to try to somehow change the mrc.cache generated by coreboot
with ME so that coreboot without ME accepts it as valid and does not
regenerate.

Marek
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