[coreboot] Nehalem not booting with two ram sticks

[Federico Amedeo Izzo]

Hello,

I have a problem with my ThinkPad X201 (nehalem)

I have two sticks of Samsung 4GB 2Rx8 PC3-10600S (1333MHz)
When i use only one of them in one of the two slots, the computer boots
fine,
but when i use both of them in the two slots, the computer doesn't boot,
the screen doens't even turn on.

I dumped the logs via EHCI but they seem normal, in fact both the
working combination and the broken one make 34 or so iterations of
Timings dumping,
but then the working conf. start booting, while the broken one freezes
without printing error messages on the EHCI.

I have tried adding more `printk` calls in
`src/northbridge/intel/nehalem/raminit.c`
but ended up in a brick, probably because i slowed down the
initialization too much.

I attach three EHCI logs:
- the first stick in the first slot: working
- the second stick in the second slot: working
- both stick inserted: not working

Also i find difficult to understand the code in `raminit.c` of nehalem
because it lacks almost completely of comments, with respect to
raminit.c of sandybridge for example.