"Todd C. Miller" <Todd.Miller@cs.colorado.edu> writes:

> 
> I have the opportunity to get a cheap multi i/o + aic6360 scsi
> VL-bus card for a 486 I'm going to be using as a PPP gateway and
> firewall.  From the source I see that the driver uses programmed I/O
> and not DMA transfers.  Can anyone using this driver tell me how
> the performance is?

The performance kind of sucks.  It would be better if the driver
supported DMA, primarily because it could then safely do synchronous
negotiation.

(There appears to be a design flaw in the chip that precludes the use
of synchronous mode with PIO.  This causes the driver to lose with
some fast devices, until a few minutes ago when I disabled synchronous
mode in -current.  I've analyzed this problem fairly thoroughly, and
sent off a few queries to Adaptec, but have received no answers at
all.)

Implementing DMA mode would be easier if the documentation for the
chip didn't also kind of suck.  To top it off, there are no drivers
for it that I can find that actually use DMA, so it's possible that it
doesn't work right either.  I personally don't have time to experiment
with it.