ofw_console4

Usage

Overview

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]

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).