Subject: com "silo overflow" messages
To: None <current-users@NetBSD.ORG>
From: Ken Raeburn <>
List: current-users
Date: 01/21/1997 12:42:59
I've been having problems off and on with silo overflow messages for a
long time.  My modem and serial ports are configured for hardware flow
control.  Michael Graff (and others, I think) suggested some time ago
that interrupt disabling for long periods in the wd driver might be
responsible.  Since the messages usually came up during periods of
heavy disk activity, this seemed to make sense.

However...  In my current configuration, I don't have a wd controller
any more.  All disks are connected to an Adaptec 2940U SCSI
controller.  And yet I still get "silo overflow" reports during heavy
disk activity.

Oh, and the system reconfiguration I did also involved swapping out
the motherboard (486/33 -> Pentium/166) and changing serial ports
(tried both my AST 4-port card and the ports on the new motherboard,
both reported to have "ns16550a, working fifo").

So I've switched out everything that seems relevant except the modem
itself.  But even if the modem has broken flow control, should the PC
have problems keeping up with a port speed of 115.2Kbps?  (In the old
configuration I tried much slower port speeds; they helped but didn't
entirely eliminate the problem.  Haven't tried that in the new setup.)

My kernel dates from mid-November.  I tried updating, but it looks
like I'll need to update some other tools first so I can build the new

Any chance the ahc driver might have problems like Michael had
suggested for the wd driver?  Any way I can tell?