On Sep 10,  9:45pm, Michael R Zucca wrote:
>Well, I'm sort of doing that by adding and subtracting code. I think it
>may have to do with link ordering. This may be a compiler or linker bug
>and it may also be a strangity of the IIvx since I have heard no other
>reports of this occuring.

A problem like this has been around for a very long time, and rears its
ugly head every so often.  You will note that there is a (commented)
	.space 0x1000
(since replaced with a .space 0x2a00 for somewhat similar reasons)
at the end of vectors.s.  This is because a frob to one of the VIAs was
hammering a location in low kernel space, so the whole kernel was moved
up a few K to get it out of the way (I found this on my Mac II).  This also
manifested itself with unpredictable errors when code was added/removed.

>This may have something to do with the fact that we're still inheriting most
>of our memory map from MacOS. In a perfect world we would write some bootstrap
>code that would absolutely size the RAM (or ask the ROMS to), find device
>and NuBus space and then zap in our own memory mapping cleanly. This would
>cause all kinds of problems with devices but if we convert all the drivers
>to use bus spaces then we can move memory about practically at will.

I recall that early attempts to size memory were frustrated by the ambiguity
of the Mac hardware, where it would fail to return the expected faults when
attempting to access non-existent memory.  That's why we're stuck with the
kluge we have now.  Allen could tell you more about this, I'm sure.

~Steve

-- 
Steven R. Allen - wormey@eskimo.com      http://www.eskimo.com/~wormey/

Faith is the quality that enables you to eat blackberry jam on a picnic
without looking to see whether the seeds move.

Contrary to popular belief, Unix is user friendly.  
It just happens to be selective about who it makes friends with.
	-Kyle Hearn  <kyle@intex.net>

You possess a mind not merely twisted, but actually sprained.