Subject: Re: Adaptec install
To: None <thorpej@nas.nasa.gov>
From: David Mazieres <dm@amsterdam.lcs.mit.edu>
List: port-i386
Date: 11/07/1995 11:51:03
> From: Jason Thorpe <thorpej@nas.nasa.gov>
> Date: Sun, 05 Nov 1995 16:37:29 -0800
> 
> Well, you must have more than 16mb in that machine.  ISA can't deal with 
> DMA beyond 16mb.  Until we have bounce buffer support (which has to be 
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> architected correctly given that we have to radically different ports 
> that use ISA), you're going to have to pull memory that's beyond 16mb, or 
> just trick the system into not using any of the extra.

Realistically speaking, is this ever going to happen?  It seems that
almost every PC I find that's more than about a year old has an
Adaptek 1542 SCSI controller in it.  Several people I know have
refused even to try NetBSD when they found out it does not support
bounce buffers.  I myself, much as I prefer NetBSD, am basically on
the verge of running FreeBSD for a while because 16 Meg just isn't
enough to do the kinds of things I do without uncomfortable swapping.
It's also a pain to keep hand editing the machdep.c file to ignore my
upper 16 Meg of RAM.

Is the philosophy here to wait until most motherboards have PCI
controller cards, or will the bounce buffer patch be integrated at
some point (is it even acceptable in its current form)?
Alternatively, are there any supported non-bus-mastering ISA SCSI
cards that would allow me to use more than 16 Meg?  I would seariously
consider buying some cheapo SCSI card if it allowed me to use all my
memory.  Or, has anyone hacked bounce buffers directly into the
Adaptek driver and made the code available?  For this particular
problem, I really don't care about elegance and would be delighted to
use garbage code if it got the job done.

Thanks,
David