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VT(4) Kernel Interfaces Manual VT(4) NAME vt -- virtual terminal system video console driver SYNOPSIS options TERMINAL_KERN_ATTR=<attribute> options TERMINAL_NORM_ATTR=<attribute> options VT_MAXWINDOWS=<N> options VT_ALT_TO_ESC_HACK=1 options VT_TWOBUTTON_MOUSE options VT_FB_MAX_WIDTH=<X> options VT_FB_MAX_HEIGHT=<Y> options SC_NO_CUTPASTE device vt In loader.conf(5): hw.vga.textmode=1 hw.vga.acpi_ignore_no_vga=1 kern.vty=vt kern.vt.color.<colornum>.rgb=<colorspec> kern.vt.fb.default_mode=<X>x<Y> kern.vt.fb.modes.<connector>=<X>x<Y> kern.vt.slow_down=<delay> screen.font=<X>x<Y> In loader.conf(5)or sysctl.conf(5): kern.consmute=1 kern.vt.kbd_halt=1 kern.vt.kbd_poweroff=1 kern.vt.kbd_reboot=1 kern.vt.kbd_debug=1 kern.vt.kbd_panic=0 kern.vt.enable_altgr=0 kern.vt.enable_bell=1 DESCRIPTION The vt device provides multiple virtual terminals with an extensive feature set: Unicode UTF-8 text with double-width characters. Large font maps in graphics mode, including support for Asian charac- ter sets. Graphics-mode consoles. Integration with KMS (Kernel Mode Setting) video drivers for switch- ing between the X Window System and virtual terminals. Virtual Terminals Multiple virtual terminals are provided on a single computer. Up to six- teen virtual terminals can be defined. A single virtual terminal is con- nected 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 cre- ated, Shift-Alt-F1 through Shift-Alt-F4 are used to switch to the addi- tional terminals. 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 fore- ground 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 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 moused(8) for more information. 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 func- tion key sequence (such as Fn + K) to access Scroll Lock. DRIVER CONFIGURATION Kernel Configuration Options These kernel options control the vt driver. TERMINAL_NORM_ATTR=<attribute> TERMINAL_KERN_ATTR=<attribute> These options change the default colors used for normal and kernel text. Available colors are defined in <sys/terminal.h>. See "EXAMPLES" below. VT_MAXWINDOWS=<N> Set the number of virtual terminals to be created to N. The value defaults to 12. 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. VT_TWOBUTTON_MOUSE If defined, swap the functions of mouse buttons 2 and 3. In ef- fect, this makes the right-hand mouse button perform a paste. These options are checked in the order shown. SC_NO_CUTPASTE Disable mouse support. VT_FB_MAX_WIDTH=<X> Set the maximum width to X. VT_FB_MAX_HEIGHT=<Y> Set the maximum height to Y. BACKWARDS COMPATIBILITY Several options are provided for compatibility with the previous console device, sc(4). These options will be removed in a future FreeBSD version. vt Option Name sc Option Name TERMINAL_KERN_ATTR SC_KERNEL_CONS_ATTR TERMINAL_NORM_ATTR SC_NORM_ATTR VT_TWOBUTTON_MOUSE SC_TWOBUTTON_MOUSE VT_MAXWINDOWS MAXCONS none SC_NO_CUTPASTE START-UP OPERATION WITH X86 BIOS SYSTEMS The computer BIOS starts in text mode, and the FreeBSD loader(8) runs, loading the kernel. If hw.vga.textmode is set, the system remains in text mode. Otherwise, vt switches to 640x480x16 VGA mode using vt_vga. If a KMS (Kernel Mode Setting) video driver is available, the display is switched to high resolution and the KMS driver takes over. When a KMS dri- ver is not available, vt_vga remains active. LOADER TUNABLES These settings can be entered at the loader(8) prompt or in loader.conf(5). hw.vga.textmode Set to 1 to use virtual terminals in text mode instead of graphics mode on BIOS boot. Features that require graphics mode, like load- able fonts, will be disabled. If a KMS driver is loaded the console will switch to, and remain in, graphics mode. Moreover this tunable has no effect with UEFI(8) boot because it does not use VGA mode. 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. kern.vty Set this value to `vt' or `sc' to choose a specific system console, overriding the default. The GENERIC kernel uses vt when this value is not set. Note that `sc' is not compatible with UEFI(8) boot. kern.vt.color.colornum.rgb Set this value to override default palette entry for color 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 "EXAMPLES" below. Note: The vt VGA hardware driver does not support palette configu- ration. kern.vt.fb.default_mode Set this value to a graphic mode to override the default picked by the vt backend. The mode is applied to all output connectors. This is currently only supported by the vt_fb backend when it is paired with a KMS video driver. kern.vt.fb.modes.<connector_name> Set this value to a graphic mode to override the default picked by the vt backend. This mode is applied to the output connector connector_name only. It has precedence over kern.vt.fb.default_mode. The names of available connector names can be found in 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 vt_fb backend when it is paired with a KMS video driver. 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. Setting 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. screen.font Set this value to the base name of the desired font file located in /boot/fonts. The font must be specified in the INDEX.fonts file located there. Fonts can be converted for use with vtfontcvt(8). 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 keymap(5) file. These settings can be entered at the loader(8) prompt or in loader.conf(5) and can also be changed at runtime with the sysctl(8) command. kern.vt.enable_altgr Enable AltGr key (do not assume right Alt key as Alt). kern.vt.kbd_halt Enable halt keyboard combination. kern.vt.kbd_poweroff Enable power off key combination. kern.vt.kbd_reboot Enable reboot key combination, usually Ctrl+Alt+Del. kern.vt.kbd_debug Enable debug request key combination, usually Ctrl+Alt+Esc. kern.vt.kbd_panic Enable panic key combination. OTHER SYSCTL TUNABLES These settings can be entered at the loader(8) prompt, set in loader.conf(5), or changed at runtime with sysctl(8). kern.consmute Disable printing kernel messages to the system console. kern.vt.enable_bell Enable the terminal bell. FILES /dev/console /dev/consolectl /dev/ttyv* virtual terminals /etc/ttys terminal initialization information /usr/share/vt/fonts/*.fnt console fonts /usr/share/vt/keymaps/*.kbd keyboard layouts DEVCTL MESSAGES System Subsystem Type Description VT BELL RING Notification that the console bell has rung. Variable Meaning duration_ms Length of time the bell was requested to ring in milliseconds. enabled true or false indicating whether or not the bell was administratively enabled when rung. hushed true or false indicating whether or not the bell was quieted by the user when rung. hz Tone that was requested in Hz. EXAMPLES To increase the scrollback buffer size to 22500 lines, add the following line to /etc/rc.conf: allscreens_flags="-h 22500" 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 im- plementation of config(8). options TERMINAL_NORM_ATTR=(FG_GREEN|BG_BLACK) 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. options TERMINAL_KERN_ATTR=(FG_LIGHTRED|BG_BLACK) To set a 1024x768 mode on all output connectors, put the following line in /boot/loader.conf: kern.vt.fb.default_mode="1024x768" To set a 800x600 only on a laptop builtin screen, use the following line instead: kern.vt.fb.modes.LVDS-1="800x600" The connector name was found in dmesg(8): info: [drm] Connector LVDS-1: get mode from tunables: info: [drm] - kern.vt.fb.modes.LVDS-1 info: [drm] - kern.vt.fb.default_mode To set black and white colors of console palette kern.vt.color.0.rgb="10,10,10" kern.vt.color.15.rgb="#f0f0f0" Load the 8x16 font in loader.conf(5) from /boot/fonts/*.fnt[.gz] at boot: screen.font="8x16" SEE ALSO kbdcontrol(1), login(1), vidcontrol(1), atkbd(4), atkbdc(4), kbdmux(4), keyboard(4), screen(4), splash(4), syscons(4), ukbd(4), kbdmap(5), loader.conf(5), rc.conf(5), ttys(5), config(8), getty(8), kldload(8), moused(8), vtfontcvt(8) HISTORY The vt driver first appeared in FreeBSD 9.3. AUTHORS The vt device driver was developed by Ed Schouten <ed@FreeBSD.org>, Ed Maste <emaste@FreeBSD.org>, and Aleksandr Rybalko <ray@FreeBSD.org>, with sponsorship provided by the FreeBSD Foundation. This manual page was writ- ten by Warren Block <wblock@FreeBSD.org>. CAVEATS Paste buffer size is limited by the system value {MAX_INPUT}, the number of bytes that can be stored in the terminal input queue, usually 1024 bytes (see termios(4)). FreeBSD ports 15.1 November 21, 2025 VT(4)
NAME | SYNOPSIS | DESCRIPTION | DRIVER CONFIGURATION | BACKWARDS COMPATIBILITY | START-UP OPERATION WITH X86 BIOS SYSTEMS | LOADER TUNABLES | KEYBOARD SYSCTL TUNABLES | OTHER SYSCTL TUNABLES | FILES | DEVCTL MESSAGES | EXAMPLES | SEE ALSO | HISTORY | AUTHORS | CAVEATS
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