Subject: Re: 1.1 386 Hardware
To: Erik M. Theisen <>
From: Michael L. VanLoon -- <>
List: current-users
Date: 11/06/1995 21:49:00
>I am planning to do a motherboard upgrade and was wondering
>about hardware limitations in the upcoming 1.1 release.  Will the 
>AIC7XXX driver support the Adaptec AHA-2842 VL-Bus SCSI card?

I would hope the driver that was just added to the tree would support
it.  Authoritative comments, anyone?

>Are mice attached to the aux. PS/2 port PROPERLY supported as I noticed 
>some caution statements in the pmc.c file.

I have no idea why that comment is there.  All the mice I've tried to
use via the PS/2 mouse port worked just fine.

>If I have a machine with
>64MB RAM will I encounter the ISA/DMA bounce buffer problem?

If you use an ISA bus-mastering card (like the AHA-1542).  ISA
addresses only 24 bits.

>Will the
>problem affect PCI DMA Bus Mastering products?

PCI is a 32-bit (addressing) bus.

>What about VL-Bus?

VLB is a 32-bit bus.  So is EISA.

>Probably will affect all ISA Bus mastering products, right?

Since the ISA bus only has 24 address lines, it would be impossible
for it not to.  Non-bus-mastering cards (i.e. the CPU does the I/O via
port reads/writes) don't suffer from this because they aren't trying
to access your memory from the other side of the bus.  But they make
the CPU spin in busy-loops reading/writing I/O port data.

>It seems absolutely TERRIBLE that bounce buffer support
>won't make it into 1.1.  It really needs to be there.

It has never been a priority for the NetBSD crowd because most serious
NetBSDers bought hardware good enough that a software hack wasn't
necessary.  If you buy good hardware, you don't need the hack.

That said, it would be really nice if this would finally get fixed.
Not everyone can afford to buy hardware to suit their software.

It was nice to see serious discussion on this subject a few weeks ago.
Hopefully it can continue soon.

  Michael L. VanLoon                       
       --<  Free your mind and your machine -- NetBSD free un*x  >--
     NetBSD working ports: 386+PC, Mac 68k, Amiga, HP300, Sun3, Sun4,
                           DEC PMAX (MIPS), DEC Alpha, PC532
     NetBSD ports in progress: VAX, Atari 68k, others...