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Minor changes and additions to the serial README file.

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This commit is contained in:
Bill Paul 1995-02-16 07:37:35 +00:00
parent c3d0cca4e9
commit fbf23e9a0b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=6486
1 changed files with 35 additions and 20 deletions
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sys/i386/boot/biosboot/README.serial
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@ -1,6 +1,7 @@
$Id$
SERIAL CONSOLE USAGE NOTES
Bill Paul (wpaul@ctr.columbia.edu)
Written by
Bill Paul <wpaul@ctr.columbia.edu>
The FreeBSD boot block can now be used to boot FreeBSD on a system with
only a dumb terminal on a serial port (COM1) as a console. This feature
@ -13,9 +14,9 @@ the changes at all (unless I've screwed something up horribly).
Note that 'options COMCONSOLE' can still be used to force the kernel to
boot in 'serial console' mode regardless of what boot options you use.
To boot FreeBSD in serial console mode, you must to the following:
To boot FreeBSD in serial console mode, you must do the following:
- Unplug your keyboard. Most PC systems probe for the keyboard during the
- UNPLUG YOUR KEYBOARD. Most PC systems probe for the keyboard during the
Power-On Self-Test (POST) and will generate an error if the keyboard
isn't detected. Additionally, many machines will pause the boot process
and wait for you to reattach the keyboard and press a key before
@ -28,7 +29,8 @@ To boot FreeBSD in serial console mode, you must to the following:
change the 'Keyboard' setting to 'Not installed' in order to bypass the
keyboard probe.
NOTE: Setting the keyboard to 'Not installed' in the CMOS configuration
NOTE #1:
Setting the keyboard to 'Not installed' in the CMOS configuration
does *NOT* mean that you won't be able to use your keyboard. All this
does is tell the BIOS not to probe for a keyboard at power-on so that
it won't bitch and moan if the keyboard isn't plugged in. You can leave the
@ -37,7 +39,16 @@ To boot FreeBSD in serial console mode, you must to the following:
to 'Not installed' only disables the BIOS's keyboard probe; it does
*NOT* actually disable the keyboard.
- Plug a dumb terminal into COM1. If you don't have a dumb terminal, you
NOTE #2:
If your system has a PS/2 mouse, chances are very good that you will
need to unplug your mouse as well as your keyboard. This is because
PS/2 mice share some hardware with the keyboard, and leaving the mouse
plugged in can fool the keyboard probe into thinking the keyboard is
still there. I have access to a Gateway 2000 Pentium 90Mhz system with
an AMI BIOS that behaves this way. In general this is not a problem
since the mouse isn't much good without the keyboard anyway.
- PLUG A DUMB TERMINAL INTO COM1. If you don't have a dumb terminal, you
can use an old PC/XT with a modem program, or the serial port on
another UNIX box. If you don't have a COM1, get one. At this time,
there is no way to select a port other than COM1 without recompiling
@ -46,19 +57,21 @@ To boot FreeBSD in serial console mode, you must to the following:
install a new boot block and kernel once you get FreeBSD up and running.
(It is assumed that COM1 will be available on a file/compute/terminal
server anyway; if you really need COM1 for something else (and you can't
switch it to COM2), then you probably shouldn't even be bothering with
all this.)
switch that something else to COM2), then you probably shouldn't even
be bothering with all this in the first place.)
NOTE #1:
The serial port settings are hardcoded to 9600 baud, 8 bits, no parity,
1 stop bit.
NOTE: in addition to a serial cable, you will need a null modem adapter
NOTE #2:
In addition to a serial cable, you will need a null modem adapter
in order to connect the terminal to the PC's serial port. If you don't
have one, go to Radio Shack and buy one: they're cheap.
- Boot the machine. The boot block will probe for a keyboard on your
- BOOT THE MACHINE. The boot block will probe for a keyboard on your
system. If it fails to find one, you'll see a prompt appear on the
terminal that looks like this:
terminal that looks something like this:
No keyboard found.
@ -84,9 +97,9 @@ To boot FreeBSD in serial console mode, you must to the following:
force the kernel to switch console devices. For instance, if you boot
from the VGA console, you can use -h to force the kernel to use the
serial port as its console device. Alternatively, if you boot from
the serial port, using -h will force the kernel to use the VGA display
as the console instead. (Can you say 'toggle' boys and girls? I knew
you could. Now try saying 'XOR.')
the serial port, you can use the -h to force the kernel to use the VGA
display as the console instead. (Can you say 'toggle' boys and girls?
I knew you could. :)
CAVEATS:
@ -97,20 +110,20 @@ CAVEATS:
AMI BIOSes can be configured to boot with no graphics adapter installed
simply by changing the 'graphics adapter' setting in the CMOS configuration
to 'Not installed.' However, many machines do not support this option
and will refuse to boot if you have no display hardware installed. With
these machines, you'll have to leave some kind of graphics card installed,
(even if it's just a junky mono board) although you won't have to plug a
monitor into it. You might also try installing an AMI BIOS. :)
and will refuse to boot if you have no display hardware in the system. With
these machines, you'll have to leave some kind of graphics card plugged in,
(even if it's just a junky mono board) although you won't have to attach
a monitor into it. You might also try installing an AMI BIOS. :)
- Using a port other than COM1 as the console requires some recompiling.
Again, it's usually assumed that COM1 will be available for use as a
console device on a dedicated file/compute/terminal server, so hopefully
you'll never have to do this. But if you feel you must change the console
you'll never need to do this. But if you feel you must change the console
to a different port, here's how:
o Get the kerndist kernel source package.
o Edit /sys/i386/boot/biosboot/Makefile and set COMCONSOLE to the
address of the port you want to use (0x3F8, 0x2E8, 0x3E8 or
address of the port you want to use (0x3F8, 0x2F8, 0x3E8 or
0x2E8). Only COM1 through COM4 can be used; multiport serial
cards will not work. No interrupt setting is needed.
o Create a custom kernel configuration file and add the following
@ -130,3 +143,5 @@ CAVEATS:
o Install the boot blocks with the disklabel command and boot
from the new kernel.
$Id: README.serial,v 1.1 1995/01/20 07:48:16 wpaul Exp $