[coreboot] To be FAM_F or not to be ?

lautriv lautriv at coldplug.net
Sat Dec 29 22:40:22 CET 2012

Hello there,
i won't annoy people with my questions here in but some of them in the IRC
repeadedly told me to ask the ML.
So here we go :

On the way of a new/changed port for a Tyan B4882 Mobo which is/was somewhat
in the supported list but with a lot of issues ( at lest for me ) i 
started over
and did it from scratch, using parts from serengeti cheetah which is 
basically the same
hardware with another CPU-Socket.

The Board in Question will be equipped with 4 dual-cores from type


this specific model is a HP-OEM CPU functionally identical to it's OSA 
but drawing just 68 instead of 95W.

it reports as Family 0x0F, Model 0x21, Stepping 0x02

so i did some minor changes
( change Socket, and FAM_F, fake a CPU_SOCKET_TYPE with 0x0a which would 
be a logical
  predecessor of 0x10 for Socket_F )

and got an error-free build.

However this code can't and won't work because S940 has no DDR2 but DDR 
and so i get
"no RAM" as assumed.
Right now i did nothing else enabling all DRAM clocks due to the lack of 
for this particular model, the Kernel and Bios Developer Guide for FAM_F 
does not even
mention Socket 940, in particular shown in the functional description from

Function2, Offset 0x88 [31:24].

The same Board/CPU boots with a slightly modified s4882 setup from the 
past which is pre_f,
pointing out either this model lacks on some register-changes or it runs 
in a somewhat compatible mode.

on the other hand, the CPU in question and a Socket_F CPU from a 
different board reporting both
the very same " DRAM Controller [1022:1102] ".

so my final "real Question" is : can anyone tell/provide more 
to shed some light in this dark place ?

P.S: from certain readings, this may also affect single-cores from 852 
and above because a bunch of
Boards did not even boot them without a bios-change, if i did not mix 
something up, we are talking
about a 90nm Italy/Egypt core with Rev. E6+.

PPS: I wish all a happy new year in a few days ;)

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