On Fri, 22 Nov 2002, Jeff Walther wrote:

> >The answer to those questions are "it depends".  The interrupt assignment
> >varies from board to board.  The top level interrupt handling code gets
> >the mapping info from Open Firmware.  As for whether there are extra pins,
> >I have no idea.
> 
> Hmmm.  Is there a listing of interrupts and their respective devices 
> for the 9500 and the 7500/8500?  

There's a mostly-complete list in the MkLinux interrupt handling code, but
even we depend on Open Firmware to flesh it out.  The best thing to do is
to just walk through the OF tree doing a ".properties" on every node and
write down all the interrupt numbers you see and what device the interrupt
is associated with.


> Is the mapping info from Open Firmware something which is coded into 
> the OF version.  That is, is it hard coded into the ROM?  Or is it 
> something that OF detects from the motherboard?

If I were gueswsing... probably hard-coded into the ROM... but I'm not
certain.


> The ROM and 
> therefore the OF for the entire x500 line and the PCC clones (except 
> PowerBase) and the Umax Storm Surge clones are all the same.   Of 
> course, the OF could have a branch in there depending on which 
> machine it finds itself installed in.

Very likely.


> >>  For example each slot in the six slot machines has it's own
> >>  interrupt.  The interrupt for each PCI slot is connected to its own
> >>  pin on Grand Central.  So three of those interrupts are not used in a
> >>  three slot machine, unless they are used by the built-in video
> >>  circuitry on the {7,8} {5,6} 00.
> >
> >That is probably, but not definitely, correct.  It does assume that only
> >one grand central variant exists.  I don't know for certain whether that
> >is true or not.
> 
> Hmmm.  The Apple part number on the Grand Central chips are all the 
> same as far as I can tell (343S1125-03).    For a more definite test 
> I could move the Grand Central chip from one model machine to another 
> and see if the recipient board still works properly.   Do you have a 
> suggestion for a donor and a recipient motherboard model which you 
> think would be a good test?

No need to do any major surgery to check that.  Just verify the chip's
part number, then verify the revision if there is one.  Probably as an OF
property.  If both of those match, then the chips are the same.  They're
probably the same.


David

---------------------------------------------------------------------
David A. Gatwood                                dgatwood@gatwood.net
Developer Docs Writer                             dgatwood@apple.com
Apple Computer                                  dgatwood@mklinux.org

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