dconschat(8)

NAME

dconschat - user interface to dcons(4)

SYNOPSIS

dconschat [-brvwRT1] [-h hz] [-C console_port] [-G gdb_port]
[-M core]
          [-N system]
dconschat  [-brvwR1] [-h hz] [-C console_port] [-G gdb_port]
[-a address]
          [-u bus_num] -t target_eui64

DESCRIPTION

The dconschat utility is designed to provide a way for users

to access
dcons(4) (dumb console device) on a local or remote system.

The
dconschat utility interacts with dcons(4) using kvm(3) or

firewire(4),
and interacts with the user over TTY or TCP/IP. To access

remote
dcons(4) using firewire(4), you have to specify target EUI64

address
using the -t option.

The dconschat utility and the dcons(4) driver communicate

using 2 ports,
one for the console port and another for remote gdb(1) port.

Users are
supposed to access dconschat using TTY, telnet(1) and

gdb(1). You can
specify listen ports for console and gdb(1) port using the

-C and -G
options respectively. The port number 0 has special meaning

that current
TTY (stdin/stdout) is used instead of TCP/IP. A negative

port number
will disable the port. To quit dconschat, send a CR + `~' +

`.' sequence
to the console port, or send signal to the process.

By analogy with pty(4) device, the dcons(4) acts as a slave

device and
dconschat acts as a master device with telnetd(8).

-b Translate Ctrl-C to ALT_BREAK (CR + `~' + Ctrl-B) on

gdb(1) port.

-r Replay old buffer on connection.

-v Verbose debug output. Multiple -v options increase

verbosity.

-w Listen on a wildcard address rather than localhost.

-R Read-only. Do not write anything to the dcons(4)

buffer.

-T Enable ad-hoc workaround for the TELNET protocol to

remove unnec

essary byte sequences. It should be set when you

access
dconschat using telnet(1).

-1 One-shot. Read available buffer, then exit. This

implies the -r

option.

-h hz Specify polling rate. The default value is 100.

-C console_port

Specify the console port. The default value is 0

(stdin/stdout).

-G gdb_port

Specify gdb(1) port. The default value is -1 (dis

abled).

-M core

Specify core file.

-N system

Specify system file such as /boot/kernel/kernel.

-t target_eui64

Specify the 64-bit extended unique identifier of the

target, and
use FireWire to access remote dcons(4).

-a address

Specify the physical I/O address of the dcons(4)

buffer. See
dcons(4) for details. If this option is not speci

fied, dconschat
tries to get the address from the Configuration ROM

on the target. You are supposed to enable dcons_crom(4) on

the target to
omit this option.

-u bus_num

Specify FireWire bus number. The default is 0.

FILES

/dev/fwmem0.0
/dev/mem
/dev/kmem

EXAMPLES

To use dconschat with FireWire for remote dcons(4), you have

to specify
the EUI64 of the target. You can obtain EUI64 by running

fwcontrol(8)
without options. The first EUI64 is of the host running fw

control(8) and
others on the bus follow.

# fwcontrol
2 devices (info_len=2)
node EUI64 status

1 77-66-55-44-33-22-11-00 0
0 00-11-22-33-44-55-66-77 1

The EUI64 does not change unless you change the hardware as

the ethernet
address.

Now we can run dconschat.

# dconschat -br -G 12345 -t 00-11-22-33-44-55-66-77

You will get console output of the target and login prompt

if a getty(8)
is running on dcons(4). You can break to DDB with ALT_BREAK

(CR + `~' +
Ctrl-B) if DDB and ALT_BREAK_TO_DEBUGGER are enabled in the

target kernel. To quit the session, type CR + `~' + `.' in the con

sole port.

Using gdb(1) port is almost the same as remote gdb(1) over

serial line
except using TCP/IP instead of /dev/cu*. See On-line Kernel

Debugging
Using Remote GDB section of The FreeBSD Developers Handbook

and gdb(4)
for details.

% gdb -k kernel.debug
(kgdb) target remote :12345

Once gdb(1) is attached and you specified the -b option to

dconschat,
typing Ctrl-C in gdb(1) causes a break to debugger.

The following command gets the console log from the crash

dump:

# dconschat -1 -M vmcore.0 -N kernel.0

If you want access to the console using telnet(1), try the

following:

# dconschat -rTC 5555 &
# telnet localhost 5555

You may want to keep logging console output of several ma

chines.
conserver-com in the Ports collection may help you. Insert

the following
lines in conserver.cf:

console local {

master localhost;
type exec;
exec /usr/sbin/dconschat -rh 25;

}
console remote {

master localhost;
type exec;
exec /usr/sbin/dconschat -rh 25 -t

00-11-22-33-44-55-66-77;

}

SEE ALSO

gdb(1), telnet(1), kvm(3), dcons(4), dcons_crom(4), ddb(4),

firewire(4),
fwohci(4), gdb(4), eui64(5), fwcontrol(8)

AUTHORS

Hidetoshi Shimokawa <simokawa@FreeBSD.org>

BUGS

This utility is currently under development.

BSD February 11, 2003

BSD