[LinuxBIOS] RAM controller breakage?

Segher Boessenkool segher at kernel.crashing.org
Sun Nov 12 00:54:19 CET 2006

> 1) I found in my testing that you can do things to the north bridge  
> that
> will crash it in such a way that a reset does not fully fix.  It's  
> very
> sneaky, things just start behaving really weird and your code just  
> seems
> to start failing for no good reason.  But not so bad as to suspect  
> that
> its hardware.  Especially if you are doinking with the register  
> settings
> at the time.
> The only fix is to _remove_ power from the board.

Many chips have debug registers (often not documented in
public literature) that seriously change the behaviour
of the chip; and such debug registers are often not reset
by a simple chip reset (which is a good thing really).
Most shipping hardware (esp. "B" or later revs) doesn't
need programming any of those registers for proper


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