[coreboot] HT_CHAIN_* woes

Arne Georg Gleditsch arne.gleditsch at numascale.com
Wed Sep 29 10:54:20 CEST 2010


I'm trying (again) to get my head around how the different pieces of
HT-enumeration interacts...  Do we have any documentation on the


and their intended/actual semantics?  The H8QIi I'm working on has a
RS780 (or 890, but I'm working from the 780 code base) SB which expects
to find itself on unit 0.  Both the existing code and the hardware seems
determined about this; rs780.c has this hard coded, and changing the
base unitid in the HT cap block appears to have no effect.

So, I'm trying to keep it there.  However, processLink in h3finit wants
to shift the devies upwards in order to discover the ncht chain --
unless the AMD_CB_ManualBUIDSwapList callback is invoked.  The
AMD_CB_ManualBUIDSwapList in ht_wrapper is only effective if
CONFIG_HT_CHAIN_UNITID_BASE is non-zero, though, which kindof makes it a
non-starter for me.  (The callback also makes some assumptions about
which HT link the SB is on that seem unwarranted.)

I think perhaps the best solution is to override the BUIDSwapList
callback in ht_wrapper, but I'm not sure what the easiest way to do that
is.  Should I just call amdHtInitialize without going through
amd_ht_init at all?  Or should we make amd_ht_init merge mainboard
specific callbacks in some way?  Thoughts welcome.


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