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Date:      Sun, 14 Nov 2004 11:38:50 +0200
From:      Ruslan Ermilov <ru@freebsd.org>
To:        Danny Braniss <danny@cs.huji.ac.il>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: boot serial console speed
Message-ID:  <20041114093850.GE84553@ip.net.ua>
In-Reply-To: <20041114083914.B43BC43D1D@mx1.FreeBSD.org>
References:  <20041114083914.B43BC43D1D@mx1.FreeBSD.org>

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On Sun, Nov 14, 2004 at 10:39:13AM +0200, Danny Braniss wrote:
> what's the magic encantation to set the console to 38400?
> btw, i solved my problem by just commenting out that part of the code,
> since i rely on the bios setting it.
>=20
> from src/sys/boot/i386/boot0/Makefile:
>=20
> # Comm settings for boot0sio.  0xE3 =3D> 9600 8-N-1
> # XXX: We should create a build-tool or something to convert BOOT_CONSOLE=
_SPEED
> # and BOOT_COMCONSOLE_PORT into the correct values to define on the build
> # command line
> BOOT_BOOT0_COMCONSOLE_SPEED?=3D	0xE3
>=20
This is the value passed in the AL register to the Int 14/AH=3D00h
BIOS function:

	http://www.ctyme.com/intr/rb-0811.htm

: Bit(s) Description     (Table 00300)
: 7-5    data rate (110,150,300,600,1200,2400,4800,9600 bps)
: 4-3    parity (00 or 10 =3D none, 01 =3D odd, 11 =3D even)
: 2      stop bits (set =3D 2, clear =3D 1)
: 1-0    data bits (00 =3D 5, 01 =3D 6, 10 =3D 7, 11 =3D 8)

0xE3 =3D 111-00-0-11 =3D 9600 bps, no parity, 1 stop bit, 8 data bits

But I think it's not possible to set it to anything above 9600 bps
using this BIOS call.


Cheers,
--=20
Ruslan Ermilov
ru@FreeBSD.org
FreeBSD committer

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