[coreboot] what should CONFIG_HT_CHAIN_UNITID_BASE be in "CPU/1HT device" mode?

[Myles Watson]

> There is just the CPU and 690 or 780. The AMD 600 or 700 is connect
> with Alink, not HT.
You're right.  I didn't look closely enough.

> > early_ht.c: Just enumerate the southbridge chain in case that's needed
> for
> > serial initialization or ROM access.
> >
> > incoherent_ht.c: Enumerate all chains so that they can be optimized
> before
> > the first reset.
> >
> > hypertransport.c: Enumerate the chains according to the device tree.
> 
> Is early_ht.c, enumerate_ht_chain(), even needed. The subtractive path
> should work. Maybe depends on the southbridge/configuration.
For K8, early_ht.c doesn't even get compiled in if you set
CONFIG_HT_CHAIN_UNITID_BASE to 0.

It's needed for the case where there is a tunnel, then the southbridge.
Serengeti Cheetah is a good example.  You can't get to the southbridge until
you've moved the 8131 or 8132 out of the way.

> For Fam10, I think that where problems happen is the early_ht.c sets
> values that are found and used by the AGESA based code that has a
> slightly different search algorithm. This happens in ht3init.c,
> process_link(). Failures in process_link() cause the system to halt
> even if it could continue based on the early setup.
I wish I knew more about Fam10, but I don't have a board, so I haven't been
that motivated to look into it further.

Thanks,
Myles