Subject: Re: Another changer, another changer problem
To: NetBSD-current Discussion List <>
From: Greg A. Woods <>
List: current-users
Date: 10/03/1998 00:55:58
[ On Fri, October 2, 1998 at 21:32:49 (-0700), Curt Sampson wrote: ]
> Subject: Re: Another changer, another changer problem 
> 3cocm ards on PCI buses attach in bus and slot order.

If they can do it, why can't all PCI cards???

I realize that it is impossible to tell what slot belongs to what bus on
some motherboards, at least just by looking (my primary experience comes
from the Asus PII97, which is far from what logic would suggest), but
that's not to say all machines with PCI will be so brain damaged.

Certainly CompactPCI machines will have a definite slot order, though
whether it can be determined from the software side is something I've
yet to find out.

> Well, that would cover a hell of a lot of the machines we run on,
> if not all of them. What's the point of implementing your scheme
> if it's useless on most machines?

That's a good question, though I question your bias somewhat.  It may be
based on counts of actual machines, but it seems not on counts of
architectures.  Certainly the sparc and some m68k machines (incl. sun3)
are more predictable, as is the vax and the pmax to the best of my
memory.  What about hp300?  Certainly making a scheme such as I'm
describing be generic for such a wide variety of platforms as NetBSD
supports is not going to be easy.

Certainly what I'm suggesting makes more sense on big servers which
might actually make use of it than it does on wee personal machines.
The little guy with one IDE disk plugged into the only connector on his
motherboard isn't going to notice any improvement in device
managability.  However if I've got a big Alphaserver with a half dozen
SCSI host adapters on it, then I'm really going to appreciate the
clarity of a descriptive system.

I dunno.  Does NetBSD want to attract the LISA crowd who are doing big
24x7 operations?

> > What does Digital Unix do?  That's one platform I know where the big
> > monster servers have *many* busses and the potential for dozens, or
> > hundreds, of similar controllers?
> Same thing that NetBSD does.

Even on the machines where there are turbo-channels with EISA or PCI
busses sub-attached?

							Greg A. Woods

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