From owner-freebsd-smp  Sun Feb  1 00:20:20 1998
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	Sun, 1 Feb 1998 19:17:44 +1100
Date: Sun, 1 Feb 1998 19:17:44 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199802010817.TAA03148@godzilla.zeta.org.au>
To: ben@stuyts.nl, freebsd-smp@FreeBSD.ORG
Subject: Re: Trouble with high-speed sio
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>I've just added an additional (isa) uart board with two quad-speed 16550's to  
>my system. (Gigabyte 586DX with dual 166MMX). They are recognized by the  
>kernel:
>
>sio2 at 0x3e8-0x3ef irq 10 on isa
>sio2: type 16550A
>sio3 at 0x2e8-0x2ef irq 9 on isa
>sio3: type 16550A
>
>and they seem to work fine, but I get a few disturbing console messages:
>
>sio3: 64 events for device with no tp

This is harmless, but shouldn't happen.

>sio2: 124 more interrupt-level buffer overflows (total 124)
>sio2: 125 more interrupt-level buffer overflows (total 249)
>sio2: 125 more interrupt-level buffer overflows (total 374)
>
>sio2 runs at 460 KBaud. (Kernel thinks 115 KB)
>sio3 is unused / not-connected.

460000 bps is not supported.  There is only enough interrupt-level
buffering for 256000 bps at best.  crtscts should reduce the flow
to at most about 192000 bps if it works.

Bruce