console(4) - NetBSD Manual Pages

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CONS(4)               NetBSD/x86 Kernel Interfaces Manual              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 con-
     sole parameters to the kernel.

     As of NetBSD 1.5, the consdev bootblock command allows changing the con-
     sole 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.

NetBSD 10.1                    September 6, 2006                   NetBSD 10.1