NAME

ofw_console —

Open Firmware console

SYNOPSIS

cpu AIM
options OFWCONS_POLL_HZ=N

options KDB
options DDB
options ALT_BREAK_TO_DEBUGGER

DESCRIPTION

The ofw_console driver provides a simple text console, using the Open Firmware services for input and output. It will use the Open Firmware console devices set via the input-device and output-device variables.

This driver is deprecated and only provided as a fallback console mechanism if the real console hardware can not be driven by FreeBSD.

In case the ofw_console console appears to work too slowly, its responsiveness probably can be improved by including options OFWCONS_POLL_HZ=N. When omitted, OFWCONS_POLL_HZ defaults to 4. For example, on Sun Ultra 2 a value of 20 or higher works best. Too high values, on the other hand, can cause ofw_console to unnecessarily consume CPU.

FILES

/dev/console
/dev/keyboard: terminal input device in case the console input device is the keyboard
/dev/screen: terminal output device in case the console output device is the screen
/dev/tty[a-z]: terminal device in case both the console input and output device is tty[a-z]

HISTORY

The ofw_console driver first appeared in FreeBSD 5.0.

AUTHORS

The ofw_console driver was written by Benno Rice <benno@FreeBSD.org>.

CAVEATS

Since the Open Firmware will handle BREAK (or Stop-A) sequences before ofw_console, the preferred way to enter ddb(4) when using ofw_console is to include options ALT_BREAK_TO_DEBUGGER in a ddb-enabled kernel, and enter the alternate BREAK sequence (RETURN TILDE CTRL-b).

BUGS

The ofw_console driver also not attach to the hardware resources it actually talks to.