[coreboot] Lenovo Thinkpad X201: Coreboot incompatible with me_cleaner

[Sam Kuper]

Dear all,

I have been investigating booting my X201 on two axes:

- Coreboot vs stock BIOS

- Intel Management Engine left alone vs neutralised with me_cleaner.

Of the four quadrants created by those two axes, only one quadrant
does not work: Coreboot + neutralised ME:

- Stock BIOS: boots fine.

- Stock BIOS, neutralised: doesn't boot boots fine after a delay of <1 minute.

- Coreboot with SeaBIOS payload, based on descriptor & ME regions from
stock BIOS: boots fine.

- Coreboot with SeaBIOS payload, based on descriptor & ME regions from
neutralised BIOS: **doesn't boot**.

See additional details here, including the output of intelmetool:
https://github.com/corna/me_cleaner/issues/24 .

Nicola Corna pointed out to me that adding a timeout at
https://github.com/coreboot/coreboot/blob/master/src/northbridge/intel/nehalem/raminit.c#L1756
might solve this problem.

(I guess the idea is that instead of waiting indefinitely for the ME
to load, Coreboot should instead just wait for a defined amount of
time and then plough on regardless.)

I am not a C programmer, so am not competent to add that timeout.

Please can anyone here provide a suitable patch for me to test, or
failing that, point me to a similar timeout in another architecture's
raminit that I might use as a starting point?

Thanks,

Sam