> From: P Kern <pkern@utcc.utoronto.ca>
> Date: 	Wed, 11 Sep 1996 17:40:44 -0400
> 
> Hello.  I've just installed 1.2_BETA on a 3/280.
> The 3/280 has a SCSI boot disk. It also has an SMD disk via a 7053 ctlr.
> The SMD disk seems to work ok during fsck's or when just lightly poking
> around, but whenever I try to do some serious activity (eg. disk-to-disk
> copying), the following types of messages show up on the console:
> 
> 	xdc0: warning: out of DVMA space
[...]
> 
> The target data on the SMD disk seems to be okay (according to cmp(1)).
> 
> Have these types of messages been seen before?
> Are they just left-over debugging messages
> or is this something more serious?
> 
> Thanks in advance.

It's fairly serious.  The interface between drivers and the DVMA
module needs to change.  The Sun3 has only a relatively small DVMA
space, so the kernel needs to either:
(1) Have drivers permanently allocate DVMA space at attach time, or
(2) Come up with a way for driver interrupt routines to wait for
    the required DVMA space before starting the next transfer.

I think I can do (1) fairly easily, and that will allow up to 3
controllers or so.  Doing (2) would be better, but would really
need kernel threads to do nicely, so the driver could just use a
"work" thread to do transfers, so the "work" thread can block on
resource shortages (like DVMA space).  That's a long way off...

Gordon