Subject: Re: Another changer, another changer problem
To: NetBSD-current Discussion List <>
From: Curt Sampson <>
List: current-users
Date: 10/08/1998 13:38:49
On Thu, 8 Oct 1998, Greg A. Woods wrote:

> I realize what you're saying, but generally speaking most systems will
> not have more than the maximum of four physical devices attached to any
> given PCI bus....

Huh? A machine right beside me has a five-slot motherboard, with
two more devices on the motherboard itself. That's seven packages
on this machine.

And what's the good of your scheme if it works on `most' sytems,
but not `all' systems. What we have now lets us hardwire anything,
and is extremely general. I would not want to replace that with a
scheme that's less general. Also, how do you deal with exceptions
(such as the large system that really does have a dozen controllers
spread across several different PCI buses)?

Perhaps you could write up a detailed paper explaining in detail
exactly how your proposed system would work. A large part of the
problem I have with your scheme is I see a lot of hand-waving in
the areas where I see serious problems.

> Perhaps a compile-time flag to select whether or not muliple controllers
> per slot is supported or not would help here.

Now we're back to compiling a new kernel again!

> ...AIX -- make everything
> as big as it can be and build in efficient virtual memory support for
> the kernel too.  It might not be "pretty", but it definitely works, and
> if you get a really big and honkin' machine you don't really care anyway.

Actually, I'd have no objection to doing this sort of thing with
some of our kernel data structures, assuming it wouldn't be a big
drain on efficiency.

Curt Sampson  <>  604-257-9400    De gustibus, aut bene aut nihil.
Any opinions expressed are mine and mine alone.
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