[coreboot] X201i RAM upgrade not working

Vladimir 'φ-coder/phcoder' Serbinenko phcoder at gmail.com
Fri Sep 5 23:37:27 CEST 2014

On 06.09.2014 00:19, ron minnich wrote:
> I don't think it's random at all. Vladimir can confirm, but if he is
> caching the RAM parameters, then this 'solution' will work for you
> until the next time you reflash coreboot, or change your dram type, at
> which point it will stop working.
Nehalem code discards cache if there is any mismatch between cache and
modules. There are 2 techniques in use:
1) If SPD mismatches, cache is discarded, so plugging new module will
discard cache.
2) Series of witnesses ensure that cache is only used if full algorithm
would yield the same result. E.g. if the result is a middle of timing
segment, then it saves the ends of segments and checks on next boot that
ends are the same. So even reseating the modules is likely to cause
cache to be discarded.

I think that his problem is either:
1) Badly seated modules
2) Only one permutation fails.
3) Code bug triggered by specific insertion of the said module
Since I've spent countless hours will all kinds of modules inserted and
reinserted on nehalem and the only bug I'm aware of is triggered by
having over 8G (maximum for nehalem) worth of RAM which causes die()
instead of proper ignore of extra RAM, without proof to contrary I'd
guess 1 is the case.

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