[coreboot] 8 GB DIMMs on Nehalem (Arrandale)

[Stefan Tauner]

Hi Vladimir,

since you have REed the raminit for Nehalem I'd like you to ask if you
have any knowledge, information or pointers about using 8 GB DIMMs with
it or even using more than 8 GB in total. In my case it is about an
Arrandale i5-520M (in a Thinkpad 410s).

I know that an i7-820QM (Clarksfield) is perfectly capable of working
with 8 GB DIMMs and probably up to 32 GB or even more (the Thinkpad
W510 has 4 DIMM slots and I have tested it with 20 GB) and that is from
around the same time as the Arrendale chips - which does not mean
anything but I still refuse to accept that Nehalem is that limited. The
official specs are not trustworthy IMHO and cpuid(1) and /proc/cpuinfo
show the same physical address width of 36 bits (which would indicate a
maximum of 64 GB).

The current raminit for Nehalem in coreboot is not able to train the two
8 GB DIMMs I have tested so far. I have added a debug output to
choose_reg178 in the first loop before the margins are compared to
STANDARD_MIN_MARGIN that shows that all margins are 0. If there is
anything I could try or information I can provide, please let me know.

The (ancient) vendor firmware I've been using on the T410s does
sometimes manage to boot Linux with an 8 GB DIMM (dmesg is attached
including the e820 map), but it is quite broken and memtest86 locks up
or reboots within seconds so that's probably not a good target for RE
efforts. :)

-- 
Kind regards/Mit freundlichen Grüßen, Stefan Tauner
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: t410s_vendor_8GB_dmesg.txt
URL: <http://www.coreboot.org/pipermail/coreboot/attachments/20170121/f09eeebb/attachment-0001.txt>