.\"-
.\" SPDX-License-Identifier: BSD-2-Clause
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.\" Copyright (c) 2014 Warren Block
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.Dd July 7, 2024
.Dt "VT" 4
.Os
.Sh NAME
.Nm vt
.Nd virtual terminal system video console driver
.Sh SYNOPSIS
.Cd "options TERMINAL_KERN_ATTR=_attribute_"
.Cd "options TERMINAL_NORM_ATTR=_attribute_"
.Cd "options VT_MAXWINDOWS=N"
.Cd "options VT_ALT_TO_ESC_HACK=1"
.Cd "options VT_TWOBUTTON_MOUSE"
.Cd "options VT_FB_MAX_WIDTH=X"
.Cd "options VT_FB_MAX_HEIGHT=Y"
.Cd "options SC_NO_CUTPASTE"
.Cd "device vt"
.Pp
In
.Xr loader.conf 5 :
.Cd hw.vga.textmode=1
.Cd hw.vga.acpi_ignore_no_vga=1
.Cd kern.vty=vt
.Cd kern.vt.color.<colornum>.rgb="<colorspec>"
.Cd kern.vt.fb.default_mode="<X>x<Y>"
.Cd kern.vt.fb.modes.<connector>="<X>x<Y>"
.Cd kern.vt.slow_down=<delay>"
.Cd screen.font="<X>x<Y>"
.Pp
In
.Xr loader.conf 5 or
.Xr sysctl.conf 5 :
.Cd kern.consmute=1
.Cd kern.vt.kbd_halt=1
.Cd kern.vt.kbd_poweroff=1
.Cd kern.vt.kbd_reboot=1
.Cd kern.vt.kbd_debug=1
.Cd kern.vt.kbd_panic=0
.Cd kern.vt.enable_altgr=0
.Cd kern.vt.enable_bell=1
.Sh DESCRIPTION
The
.Nm
device provides multiple virtual terminals with an extensive feature
set:
.Bl -item -offset indent
.It
Unicode UTF-8 text with double-width characters.
.It
Large font maps in graphics mode, including support for Asian
character sets.
.It
Graphics-mode consoles.
.It
Integration with
KMS
.Pq Kernel Mode Setting
video drivers for switching between the
.Em X Window System
and virtual terminals.
.El
.Ss Virtual Terminals
Multiple virtual terminals are provided on a single computer.
Up to sixteen virtual terminals can be defined.
A single virtual terminal is connected to the screen and keyboard
at a time.
Key combinations are used to select a virtual terminal.
Alt-F1 through Alt-F12 correspond to the first twelve virtual terminals.
If more than twelve virtual terminals are created, Shift-Alt-F1 through
Shift-Alt-F4 are used to switch to the additional terminals.
.Ss Copying and Pasting Text with a Mouse
Copying and pasting text from the screen with a mouse is supported.
Press and hold down mouse button 1, usually the left button, while
moving the mouse to select text.
Selected text is highlighted with reversed foreground and background
colors.
To select more text after releasing mouse button 1, press mouse button
3, usually the right button.
To paste text that has been selected, press mouse button 2, usually the
middle button.
The text is entered as if it were typed at the keyboard.
The
.Dv VT_TWOBUTTON_MOUSE
kernel option can be used with mice that only have two buttons.
Setting this option makes the second mouse button into the
paste button.
See
.Xr moused 8
for more information.
.Ss Scrolling Back
Output that has scrolled off the screen can be reviewed by pressing the
Scroll Lock key, then scrolling up and down with the arrow keys.
The Page Up and Page Down keys scroll up or down a full screen at a
time.
The Home and End keys jump to the beginning or end of the scrollback
buffer.
When finished reviewing, press the Scroll Lock key again to return to
normal use.
Some laptop keyboards lack a Scroll Lock key, and use a special function key
sequence (such as Fn + K) to access Scroll Lock.
.Sh DRIVER CONFIGURATION
.Ss Kernel Configuration Options
These kernel options control the
.Nm
driver.
.Bl -tag -width MAXCONS
.It Dv TERMINAL_NORM_ATTR= Ns Pa attribute
.It Dv TERMINAL_KERN_ATTR= Ns Pa attribute
These options change the default colors used for normal and kernel
text.
Available colors are defined in
.In sys/terminal.h .
See
.Sx EXAMPLES
below.
.It Dv VT_MAXWINDOWS=N
Set the number of virtual terminals to be created to
.Fa N .
The value defaults to 12.
.It Dv VT_ALT_TO_ESC_HACK=1
When the Alt key is held down while pressing another key, send an ESC
sequence instead of the Alt key.
.It Dv VT_TWOBUTTON_MOUSE
If defined, swap the functions of mouse buttons 2 and 3.
In effect, this makes the right-hand mouse button perform a paste.
These options are checked in the order shown.
.It Dv SC_NO_CUTPASTE
Disable mouse support.
.It VT_FB_MAX_WIDTH=X
Set the maximum width to
.Fa X .
.It VT_FB_MAX_HEIGHT=Y
Set the maximum height to
.Fa Y .
.El
.Sh BACKWARDS COMPATIBILITY
Several options are provided for compatibility with the previous
console device,
.Xr sc 4 .
These options will be removed in a future
.Fx
version.
.Bl -column -offset indent ".Sy vt VT_TWOBUTTON_MOUSE" ".Sy SC_TWOBUTTON_MOUSE"
.It Sy vt Option Name Ta Sy sc Option Name
.It Dv TERMINAL_KERN_ATTR Ta Dv SC_KERNEL_CONS_ATTR
.It Dv TERMINAL_NORM_ATTR Ta Dv SC_NORM_ATTR
.It Dv VT_TWOBUTTON_MOUSE Ta Dv SC_TWOBUTTON_MOUSE
.It Dv VT_MAXWINDOWS Ta Dv MAXCONS
.It none Ta Dv SC_NO_CUTPASTE
.El
.Sh START-UP OPERATION WITH X86 BIOS SYSTEMS
The computer BIOS starts in text mode, and
the
.Fx
.Xr loader 8
runs, loading the kernel.
If
.Va hw.vga.textmode
is set, the system remains in text mode.
Otherwise,
.Nm
switches to 640x480x16 VGA mode using
.Cm vt_vga .
If a KMS
.Pq Kernel Mode Setting
video driver is available, the display is switched to high resolution
and the KMS driver takes over.
When a KMS driver is not available,
.Cm vt_vga
remains active.
.Sh LOADER TUNABLES
These settings can be entered at the
.Xr loader 8
prompt or in
.Xr loader.conf 5 .
.Bl -tag -width indent
.It Va hw.vga.textmode
Set to 1 to use virtual terminals in text mode instead of graphics mode.
Features that require graphics mode, like loadable fonts, will be
disabled.
.Pp
If a KMS driver is loaded the console will switch to (and remain in)
graphics mode.
.It Va hw.vga.acpi_ignore_no_vga
Set to 1 to force the usage of the VGA driver regardless of whether
ACPI IAPC_BOOT_ARCH signals no VGA support.
Can be used to workaround firmware bugs in the ACPI tables.
Note no VGA support is only acknowledged when running virtualized.
There is too many broken firmware that wrongly reports no VGA support on
physical hardware.
.It Va kern.vty
Set this value to
.Ql vt
or
.Ql sc
to choose a specific system console, overriding the default.
The
.Pa GENERIC
kernel uses
.Nm
when this value is not set.
Note that
.Ql sc
is not compatible with
.Xr UEFI 8
boot.
.It Va kern.vt.color. Ns Ar colornum Ns Va .rgb
Set this value to override default palette entry for color
.Pa colornum
which should be in a range from 0 to 15 inclusive.
The value should be either a comma-separated triplet of
red, green, and blue values in a range from 0 to 255 or
HTML-like hex triplet.
See
.Sx EXAMPLES
below.
.Pp
Note: The
.Nm
VGA hardware driver does not support palette configuration.
.It Va kern.vt.fb.default_mode
Set this value to a graphic mode to override the default mode picked by the
.Nm
backend.
The mode is applied to all output connectors.
This is currently only supported by the
.Cm vt_fb
backend when it is paired with a KMS video driver.
.It Va kern.vt.fb.modes. Ns Pa connector_name
Set this value to a graphic mode to override the default mode picked by the
.Nm
backend.
This mode is applied to the output connector
.Pa connector_name
only.
It has precedence over
.Va kern.vt.fb.default_mode .
The names of available connector names can be found in
.Xr dmesg 8
after loading the KMS driver.
It will contain a list of connectors and their associated tunables.
This is currently only supported by the
.Cm vt_fb
backend when it is paired with a KMS video driver.
.It Va kern.vt.slow_down
When debugging the kernel on modern laptops, the screen is often
the only available console, and relevant information will scroll
out of view before it can be captured by eye or camera.
.Pp
Setting
.Va kern.vt.slow_down
to a non-zero number will make console output synchronous (ie:
not dependent on timers and interrupts) and slow it down in proportion
to the number.
.It Va screen.font
Set this value to the base name of the desired font file located in
.Pa /boot/fonts .
Fonts can be converted for use with
.Xr vtfontcvt 8 .
.El
.Sh KEYBOARD SYSCTL TUNABLES
These settings control whether certain special key combinations are enabled or
ignored.
The specific key combinations can be configured by using a
.Xr keymap 5
file.
.Pp
These settings can be entered at the
.Xr loader 8
prompt or in
.Xr loader.conf 5
and can also be changed at runtime with the
.Xr sysctl 8
command.
.Bl -tag -width indent
.It Va kern.vt.enable_altgr
Enable AltGr key (do not assume right Alt key as Alt).
.It Va kern.vt.kbd_halt
Enable halt keyboard combination.
.It Va kern.vt.kbd_poweroff
Enable power off key combination.
.It Va kern.vt.kbd_reboot
Enable reboot key combination, usually Ctrl+Alt+Del.
.It Va kern.vt.kbd_debug
Enable debug request key combination, usually Ctrl+Alt+Esc.
.It Va kern.vt.kbd_panic
Enable panic key combination.
.El
.Sh OTHER SYSCTL TUNABLES
These settings can be entered at the
.Xr loader 8
prompt, set in
.Xr loader.conf 5 ,
or changed at runtime with
.Xr sysctl 8 .
.Bl -tag -width indent
.It Va kern.consmute
Disable printing kernel messages to the system console.
.It Va kern.vt.enable_bell
Enable the terminal bell.
.El
.Sh FILES
.Bl -tag -width "/usr/share/vt/keymaps/*.kbd" -compact
.It Pa /dev/console
.It Pa /dev/consolectl
.It Pa /dev/ttyv*
virtual terminals
.It Pa /etc/ttys
terminal initialization information
.It Pa /usr/share/vt/fonts/*.fnt
console fonts
.It Pa /usr/share/vt/keymaps/*.kbd
keyboard layouts
.El
.Sh DEVCTL MESSAGES
.Bl -column "System" "Subsystem" "Type" "Description"
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li VT Ta BELL Ta RING Ta
Notification that the console bell has rung.
.El
.Bl -column "duration_ms" "Meaning"
.Sy "Variable" Ta Sy "Meaning"
.It Li duration_ms Ta Length of time the bell was requested to ring in milliseconds.
.It Li enabled Ta true or false indicating whether or not the bell was administratively enabled when rung.
.It Li hushed Ta true or false indicating whether or not the bell was quieted by the user when rung.
.It Li hz Ta Tone that was requested in Hz.
.El
.Sh EXAMPLES
This example changes the default color of normal text to green on a
black background, or black on a green background when reversed.
Note that white space cannot be used inside the attribute string
because of the current implementation of
.Xr config 8 .
.Pp
.Dl "options TERMINAL_NORM_ATTR=(FG_GREEN|BG_BLACK)"
.Pp
This line changes the default color of kernel messages to be bright red
on a black background, or black on a bright red background when reversed.
.Pp
.Dl "options TERMINAL_KERN_ATTR=(FG_LIGHTRED|BG_BLACK)"
.Pp
To set a 1024x768 mode on all output connectors, put the following line in
.Pa /boot/loader.conf :
.Pp
.Dl kern.vt.fb.default_mode="1024x768"
.Pp
To set a 800x600 only on a laptop builtin screen,
use the following line instead:
.Pp
.Dl kern.vt.fb.modes.LVDS-1="800x600"
.Pp
The connector name was found in
.Xr dmesg 8 :
.Pp
.Dl info: [drm] Connector LVDS-1: get mode from tunables:
.Dl info: [drm]   - kern.vt.fb.modes.LVDS-1
.Dl info: [drm]   - kern.vt.fb.default_mode
.Pp
To set black and white colors of console palette
.Pp
.Dl kern.vt.color.0.rgb="10,10,10"
.Dl kern.vt.color.15.rgb="#f0f0f0"
.Pp
Load the 8x16 font in
.Xr loader.conf 5
from
.Pa /boot/fonts/*.fnt[.gz]
at boot:
.Pp
.Dl screen.font="8x16"
.Sh SEE ALSO
.Xr kbdcontrol 1 ,
.Xr login 1 ,
.Xr vidcontrol 1 ,
.Xr atkbd 4 ,
.Xr atkbdc 4 ,
.Xr kbdmux 4 ,
.Xr keyboard 4 ,
.Xr screen 4 ,
.Xr splash 4 ,
.Xr syscons 4 ,
.Xr ukbd 4 ,
.Xr kbdmap 5 ,
.Xr loader.conf 5 ,
.Xr rc.conf 5 ,
.Xr ttys 5 ,
.Xr config 8 ,
.Xr getty 8 ,
.Xr kldload 8 ,
.Xr moused 8 ,
.Xr vtfontcvt 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 9.3 .
.Sh AUTHORS
.An -nosplit
The
.Nm
device driver was developed by
.An \&Ed Schouten Aq Mt ed@FreeBSD.org ,
.An \&Ed Maste Aq Mt emaste@FreeBSD.org ,
and
.An Aleksandr Rybalko Aq Mt ray@FreeBSD.org ,
with sponsorship provided by the
.Fx
Foundation.
This manual page was written by
.An Warren Block Aq Mt wblock@FreeBSD.org .
.Sh CAVEATS
Paste buffer size is limited by the system value
.Brq Dv MAX_INPUT ,
the number of bytes that can be stored in the terminal
input queue, usually 1024 bytes
(see
.Xr termios 4 ) .