*BSD News Article 41556


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From: iverson@lionheart.com (Tim Iverson)
Subject: Re: FreeBSD/NetBSD as terminalserver
References: <3f9khg$4s5@lxki.neutron.com>
Organization: Lionheart Software
Date: Tue, 24 Jan 1995 09:54:10 GMT
Message-ID: <D2wM6A.7Bn@lionheart.com>
Lines: 30

In article <3f9khg$4s5@lxki.neutron.com>,
Thorsten Laux <laux@neutron.com> wrote:
>I am thinking about using NetBSD/FreeBSD as a terminalserver. Is BSD
>serial io stable enough to handle one or two 4-port cards using 16550s
>at 38400 bps? Is full hardware handshaking (rts/cts/cdc) availible
>(the faq says this is not so)? How much cpu power would be necessary?

The FreeBSD-2.0-950112-SNAP sio driver has a bug that causes it to discard
characters even if RTS/CTS flow is enabled.  This happens all the time at
115200 baud.  I suspect it would still happen at 38400, just not so often.

Since I absolutely require a SIO driver with perfect HW flow control, I'll
be fixing this soon - probably next week if someone else doesn't jump
forward with a fix ;-).  I'll also be adding a null-modem support option:
don't assert DTR until DCD on dialin.  That way I can test SLIP/PPP in-house
before sic'ing my system on the internet.

BTW, despite the bug, I'm very pleased with most of the other parts of the
driver, especially the method used to establish initial and locked states
for SIO devices.  Very nice, elegant even.

>Could a 486/40 Mhz for example handle a AST 4-Port card at 38400 baud?

Disk IO will slow things down - you won't get a full 38400 on all ports if
your system is loaded with swapped out or large-vm jobs.  If you have the
memory to avoid the disk, I suspect you'll have no problem.


- Tim Iverson
  iverson@lionheart.com