CONS(4)

NAME
console - x86 console interface

SYNOPSIS
options CONSDEVNAME=string
options CONADDR=integer
options CONSPEED=integer
options CONS_OVERRIDE
options CONMODE=integer

DESCRIPTION
The “console” device is used for kernel printf messages and accesses to the /dev/console character special device in user mode. It is attached to a hardware interface at boot time controlled by options in the kernel configuration file, or information passed by the boot loader.

Bootblocks from NetBSD 1.4 or newer select their console device from a compiled-in list, and then pass their choice of console device and console parameters to the kernel.

As of NetBSD 1.5, the consdev bootblock command allows changing the console device on-the-fly.

The kernel will use the same console device as the bootblock; no special kernel configuration is required.

To override the bootblock's choice of console, or to use a serial kernel console with older bootblocks, you must specify kernel config-file options to override the information passed by the bootblock. The current option choices are:

- the standard PC keyboard and display
    (with either the “pc” or the wscons(4) driver)

- standard PC serial ports
    (with com(4) driver)

The available kernel configuration options are:

options CONSDEVNAME=string
specifies the name of the console device. Valid values are “pc” for the pc keyboard / display (default) and “com” for a serial port.

options CONADDR=integer
sets the base address for the serial console port (default: 0x3f8).

options CONSPEED=integer
sets the baudrate for the serial console (default: 9600).

options CONS_OVERRIDE
causes console information passed by the bootloader to be ignored and the settings specified by the three options above (or the defaults) to be used. Default behaviour is to use the settings from the bootloader if present, and to use option / default values only if no information was passed.

options CONMODE=integer
allows to specify terminal control flags. The argument is a “cflag” value, see termios(4) for details. Default is (CREAD | CS8 | HUPCL) (8N1). This option takes always effect, because mode settings are not passed by the bootloader.

FILES

/dev/console

EXAMPLES
options CONSDEVNAME="\"com\"",CONADDR=0x2f8,CONSPEED=57600

SEE ALSO
config(1), tty(4), boot(8)

BUGS
The console device is chosen early in system startup regardless if the specified driver / device is present in the system configuration file. If the driver asked for by the bootloader or “options CONSDEVNAME” is not configured into the system, a panic is caused. Because there is no console device, no explaining message will be printed. If the driver is present, but the specific device instance not, kernel printf will work, but /dev/console becomes a dummy.