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From: brian@shift.utell.net (Brian Somers)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Highest supported baud rate on serial line?
Date: Mon, 7 Jul 1997 15:19:52 +0100
Organization: Awfulhak Ltd.
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In article <87d8ows443.fsf@localhost>,
gorski@poboxes.com writes:
>
>
> I tried to use pppd with baud rates greater 115200 and it exists with:
> Jul 6 14:43:59 pppd[2997]: tcsetattr: Invalid argument
>
> This looks for me that the baud rate maximum is 115200!
> Then I decided to patch sio.c:
>
> ------------------------------------------------------------------------------
> *** /sys/i386/isa/sio.c Sun Jul 6 14:55:43 1997
> --- sio.c Sun Jul 6 15:14:28 1997
> ***************
> *** 359,367 ****
> { 38400, COMBRD(38400) },
> { 57600, COMBRD(57600) },
> { 115200, COMBRD(115200) },
> - { 230400, COMBRD(230400) },
> - { 460800, COMBRD(460800) },
> - { 921600, COMBRD(921600) },
> { -1, -1 }
> };
>
> --- 359,364 ----
> ------------------------------------------------------------------------------
>
>
> Result: pppd is quite and the serial line(with NS16550) works without
> any problems. Why isn't this done before by someone else? Should I
> expect any errors with these higher baud rates?
>
>
> Any hints/information?
I'm sure it's trickier than that. The UART has a register for
setting the speed where the lower the value you write there, the
faster the setting. 115200 is 1 in this register (or was it
zero).
I suspect the above has just confused the COMBRD macro.
> Thanks.
>
> - Achim
>
>
--
Brian <brian@awfulhak.org> <brian@freebsd.org>
<http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour !