Subject: Re: Proposed extension to bus.h interface
To: None <tech-kern@NetBSD.ORG>
From: Christoph Badura <>
List: tech-kern
Date: 08/19/1996 16:19:00
Jason Thorpe writes:
>On Thu, 15 Aug 1996 12:00:00 -0700 (PDT) 
> "Eduardo E. Horvath" <> wrote:
> > Wouldn't bus_io_{alloc,free}() be better as bus_mem_{alloc,free}() with
> > a different chipset tag?  All you're doing is allocating from a different
> > address space.

>No, because the chipset tag identifies the bus, in the particular case 
>I'm thinking about, "ISA", or a particular implementation of "ISA".  
>Otherwise, by your suggestion, we'd only have bus_mem_*(), and the 
>bus_io_*() functions would be gone completely.


As you might be aware, the NCR/Symbios 53C8xx chips support _both_
memory mapped and io mapped configurations.  It is conceivable that a
machine with two of these chips installed might have one of them in
the memory mapped mode and the other in the io mapped mode.

This is impossible to support with the current interface.

Granted, it is probably not desirable and I haven't seen a board that
maps the NCR SCSI chip in io space.

However this _is_ an issue with the "Teles" ISDN cards that are so
popular over here in Germany.  The older ones had the ISDN chips'
registers memory mapped in the ISA hole.  The newer cards have the
ISDN chips io mapped.  And of course we would like to mix both types
in the same machine.

Christoph Badura

You don't need to quote my .signature.  Everyone has seen it by now.
Besides, it doesn't add anything to the current thread.