Subject: Re: DMA beyond end of isa
To: None <explorer@flame.org>
From: David Mazieres <dm@amsterdam.lcs.mit.edu>
List: port-i386
Date: 12/26/1995 03:57:00
> X-Authentication-Warning: darkwatch.flame.org: Host localhost didn't use HELO protocol
> cc: david@mono.org, akt@doc.ic.ac.uk, port-i386@netbsd.org
> Date: Tue, 26 Dec 1995 01:37:56 -0600
> From: "Michael Graff" <explorer@flame.org>
> 
> >I, too, have 32Mb and an aha1542.  I hacked machdep.c to limit my
> >memory to 16 Mb, but am basically swapping constantly.  Can you say
> >something about how different OpenBSD is from NetBSD and how hard it
> >was to switch?
> 
> According to the www page, the only change was the 1542 one.

The only architecture-dependent change is the 1542 one, but there are
probably architecture-independent changes.  (Especially since there
have been a number of updates to NetBSD recently, and OpenBSD might
not be able to track all of them.)

> I have to ask the following question:  Does anyone use the 154x series
> in something other than a i386?  If not, why the hell can't we use the
> patch that was sent in for this?

A while ago I exchanged mail with someone who was using a 1542 on some
old Sun machine with an ISA bus (I think a sun3--not a 386 machine).
On the other hand, a 386-specific solution would probably solve the
problem for 90% of the users (at least until people start using the
ISA bus on alphas).

> >First, is it possible to run an OpenBSD kernel with the rest of the
> >system (including init, ps, netstat, etc.) from NetBSD?
> 
> Prolly, but let's try to fix the problem, not switch OS's yet.  I
> still think NetBSD is the one to stay with for now...

This was my attitude 2 years ago.  Since then most of the people I've
seen set up development environments on PC's have refused to consider
NetBSD because of its lack of support for the 1542.  Now the PC's
around me are all running Linux, which means all my compiles run on a
single, 16 Meg NetBSD machine which of course swaps quite heavily
under the kinds of programs I like to run.

At this point, I have two hopes:  A quick, small, and dirty patch (one
I can apply each time I sup), or a new operating system that fulfills
my needs.  OpenBSD seems to be both :-).

> >Alternatively, where are the bounce buffers implemented in OpenBSD?  I
> >downloaded the actual aha1542 driver but it was identical to the
> >NetBSD one.  Is there some piece of code from OpenBSD that I can drop
> >into the NetBSD kernel?  (I don't care how inelegant it is--I need to
> >stop swapping!)
> 
> I agree totally, but I thought the aha1542 driver was different.  Is
> there a second copy stored in the i386 tree for OpenBSD or something?

I just took the one out of the dev directory.  Is there one under
arch/i386 somewhere?

Thanks,
David