Re: vsbus doc?

>>> The major piece I'm aware of at the moment that I don't understand
>>> is the hardware backing (what 4.0.1 and 5.2 call) vsbus.  [...]
>> Ragge can preobably make a better comment on this, but my
>> recollection/understanding is that "vsbus" is just an artificial
>> name since you need some kind of bus to hang all the drivers off,
>> and you need to call it something.

>> Not sure how much, if anything actual physical represents this.  But
>> it holds the I/O space, and manages DMA.

> correct Johnny, the "vsbus" was just to hang devices on which needed
> the vaxstation properties (interrupt registers, DMA, ...).

Then I think it's the "vaxstation properties" that I'm interested in
doc on.  I found some code which seemed to imply that vsbus managed,
among other things, some kind of interrupt arbitrator/controller and
something bearing on DMA.  Whether they're thought of as separate
things or a single thing with multiple interfaces isn't really very
important.

Basically, what I'm looking for is the documentation necessary to
backport 3100/80 support.  The stuff vsbus manages is just the biggest
piece I'm presently aware I'm lacking.

> Uba/mba/bi/sbi/vsbus/... are just all handled as buses with different
> properties.

That much I did know.  (I even created two pseudo-buses of my own, at
different times and for different purposes, one as a place for things
to attach which needed an attachment - I forget why - and one to deal
with hardware which was basically a standard serial port chip (16550
maybe?) but with the inter-register addressing stride being, IIRC, four
times what it usually is for that chip - I dealt with it with some
bus-space hackery.)

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