Passes RAM test, but hangs at jumping to RAM

[SONE Takeshi]

On Thu, May 15, 2003 at 08:01:01AM -0600, ron minnich wrote:
> On Thu, 15 May 2003, SONE Takeshi wrote:
> 
> > What could be a problem when it passes RAM test but hangs 
> > immediately after jumping to RAM?
> > 
> > I'm developing a new raminit code and
> > this happens only with a particular installation of DIMM.
> > DIMM itself is not bad, it works when move to another slot,
> > or another slot is filled with another DIMM.
> > Award BIOS runs just fine with this DIMM installation.
> 
> Every time I've seen this it is either drive strength settings or timing 
> (esp. on the 8601, it is VERY sensitive to buffer strength). 

I've found 0x6B is once asssigned the same value as Aword, then
rewritten later with different value. (it's from CVS's raminit.inc)
I thought this is something to do with drive strength (changes slew rate)
but removing the latter one doesn't really change things.

I also tried COMFIG_COMPRESS=0, then Steve M. Gehlbach's copy-verify
hack (found here:
http://www.clustermatic.org/pipermail/linuxbios/2002-October/000527.html ),
and totally disabling cache.
Everytime I change something, it stops execution at different point.

> You really need to dump the northbridge and make sure you know exactly, 
> for each setting, why award set it one way and why linuxbios set it the 
> same way or differently. This is very tedious but it is your only choice. 
> With the 8601 I saw one case where all the bits except one were correct on 
> a data read. It only takes on wrong bit, however, to wreak havoc.

Thanks. I'll again have to look at those hexadecimal dumps and the book.
It really exhausts my eyes...

--
Takeshi