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SYSCONS(4) Device Drivers Manual SYSCONS(4)

syscons, sc — the console driver

options MAXCONS=N
options SC_ALT_MOUSE_IMAGE
options SC_DISABLE_DDBKEY
options SC_DISABLE_REBOOT
options SC_HISTORY_SIZE=N
options SC_MOUSE_CHAR=C
options SC_NO_CUTPASTE
options SC_NO_FONT_LOADING
options SC_NO_HISTORY
options SC_NO_SYSMOUSE
options SC_PIXEL_MODE
options SC_TWOBUTTON_MOUSE
options SC_NORM_ATTR=_attribute_
options SC_NORM_REV_ATTR=_attribute_
options SC_KERNEL_CONS_ATTR=_attribute_
options SC_KERNEL_CONS_REV_ATTR=_attribute_
options SC_BORDER_COLOR=_attribute_
options SC_DFLT_FONT
makeoptions SC_DFLT_FONT=_font_name_
device sc0 at isa? [flags flags]

The syscons driver provides multiple virtual terminals. It resembles the SCO color console driver.

The syscons driver is implemented on top of the keyboard driver (atkbd(4)) and the video card drivers (i915kms(4), radeonkms(4), or vga(4)). Please see DRIVER CONFIGURATION below on how to make the console work with i915kms(4) or radeonkms(4).

There can be only one syscons device defined in the system.

The syscons driver provides multiple virtual terminals which appear as if they were separate terminals. One virtual terminal is considered current and exclusively occupies the screen and the keyboard; the other virtual terminals are placed in the background.

In order to use virtual terminals, they must be individually marked ``on'' in /etc/ttys so that getty(8) will recognize them to be active and run login(1) to let the user log in to the system. By default, only the first eight virtual terminals are activated in /etc/ttys.

You press the Alt key and a switch key to switch between virtual terminals. The following table summarizes the correspondence between the switch key and the virtual terminal.

Alt-F1   ttyv0      Alt-F7   ttyv6      Shift-Alt-F1   ttyv10
Alt-F2   ttyv1      Alt-F8   ttyv7      Shift-Alt-F2   ttyv11
Alt-F3   ttyv2      Alt-F9   ttyv8      Shift-Alt-F3   ttyv12
Alt-F4   ttyv3      Alt-F10  ttyv9      Shift-Alt-F4   ttyv13
Alt-F5   ttyv4      Alt-F11  ttyv10     Shift-Alt-F5   ttyv14
Alt-F6   ttyv5      Alt-F12  ttyv11     Shift-Alt-F6   ttyv15

You can also use the ``nscr'' key (usually the PrintScreen key on the AT Enhanced keyboard) to cycle available virtual terminals.

The default number of available virtual terminals is 16. This can be changed with the kernel configuration option MAXCONS (see below).

Note that the X server usually requires a virtual terminal for display purposes, so at least one terminal must be left unused by getty(8) so that it can be used by the X server.

The syscons driver, in conjunction with the keyboard driver, allows the user to change key definitions and function key strings. The kbdcontrol(1) command will load a key definition file (known as ``keymap'' file), dump the current keymap, and assign a string to a function key. See keyboard(4) and kbdmap(5) for the keymap file.

You may want to set the keymap variable in /etc/rc.conf.local to the desired keymap file so that it will be automatically loaded when the system starts up.

For most modern video cards, e.g. VGA, the syscons driver and the video card driver allow the user to change the font used on the screen. The vidcontrol(1) command can be used to load a font file from /usr/share/syscons/fonts.

The font comes in various sizes: 8x8, 8x14 and 8x16. The 8x16 font is typically used for the VGA card in the 80-column-by-25-line mode. Other video modes may require different font sizes. It is better to always load all three sizes of the same font.

You may set font8x8, font8x14 and font8x16 variables in /etc/rc.conf to the desired font files so that they will be automatically loaded when the system starts up.

Optionally you can specify a particular font file as the default. See the SC_DFLT_FONT option below.

If your video card does not support software fonts, you may still be able to achieve a similar effect by re-mapping the font built into your video card. Use vidcontrol(1) to load a screen map file which defines the mapping between character codes.

You can use your mouse to copy text on the screen and paste it as if it was typed by hand. You must be running the mouse daemon moused(8) and enable the mouse cursor in the virtual terminal via vidcontrol(1).

Pressing mouse button 1 (usually the left button) will start selection. Releasing button 1 will end the selection process. The selected text will be marked by inverting foreground and background colors. You can press button 3 (usually the right button) to extend the selected region. The selected text is placed in the copy buffer and can be pasted at the cursor position by pressing button 2 (usually the middle button) as many times as you like.

If your mouse has only two buttons, you may want to use the SC_TWOBUTTON_MOUSE option below to make the right button to paste the text. Alternatively you can make the mouse daemon emulate the middle button. See the man page for moused(8) for more details.

The syscons driver allows the user to browse the output which has ``scrolled off'' the top of the screen.

Press the ``slock'' key (usually ScrllLock / Scroll Lock or Pause on many keyboards) and the terminal is in the ``scrollback'' mode. It is indicated by the Scroll Lock LED. Use the arrow keys, the Page Up/Down keys and the Home/End keys to scroll buffered terminal output. Press the ``slock'' key again to get back to the normal terminal mode.

The size of the scrollback buffer can be set by the SC_HISTORY_SIZE option described below.

The syscons driver can be made to put up the screen saver if the current virtual terminal is idle, that is, the user is not typing on the keyboard nor moving the mouse. See splash(4) and vidcontrol(1) for more details.

The following tunables are available and can be set in loader.conf(5).

kern.kms_console
Setting this tunable to 0 disables experimental framebuffer support in conjunction with the i915kms(4) or radeonkms(4) drivers. It is 1 by default.
kern.kms_columns
The number of columns to use in conjunction with the i915kms(4) and radeonkms(4) drivers. The font size is scaled to match the requested number of columns. This requires kern.kms_console to be set to 1. By default, syscons tries to find a more or less pleasant looking default. Setting kern.kms_columns to a negative value turns off scaling.

The following sysctl(8) variable is available and can be either set via sysctl.conf(5) or from the command line.

kern.syscons_async
Set to 1 to enable asynchronous bulk framebuffer updates. It is intended to help with sound(4) stuttering when a high resolution syscons scrolls during playback. It is not enabled by default because on certain machines it has lead to subtle issues with for example ddb(4).

The following kernel configuration options control the syscons driver.

This option sets the number of virtual terminals to N. The default value is 16.
This option selects the alternative way of displaying the mouse cursor in the virtual terminal. It may be expensive for some video cards to draw the arrow-shaped cursor, and you may want to try this option. However, the appearance of the alternative mouse cursor may not be very appealing. Note that if you use the SC_NO_FONT_LOADING option then you must also use this option if you wish to be able to use the mouse.
This option disables the ``debug'' key combination (by default, it is Alt-Esc, or Ctl-PrintScreen). It will prevent users from entering the kernel debugger (DDB) by pressing the key combination. DDB will still be invoked when the kernel panics or hits a break point if it is included in the kernel.
This option disables the ``reboot'' key (by default, it is Ctl-Alt-Del), so that the casual user may not accidentally reboot the system.
Sets the size of back scroll buffer to N lines. The default value is 100.
Unless the SC_ALT_MOUSE_IMAGE option above is specified, the syscons driver reserves four consecutive character codes in order to display the mouse cursor in the virtual terminals in some systems. This option specifies the first character code to C to be used for this purpose. The default value is 0xd0. A good candidate is 0x03.
Adds support for pixel (raster) mode console. This mode is useful on some laptop computers, but less so on most other systems, and it adds substantial amount of code to syscons. If this option is NOT defined, you can reduce the kernel size a lot.
If you have a two button mouse, you may want to add this option to use the right button of the mouse to paste text. See Mouse Support and Copy-and-Paste above.
 
 
 
 
These options will set the default colors. Available colors are defined in <machine/pc/display.h>. See EXAMPLES below.
This option will specify the default font. Available fonts are: iso, iso2, koi8-r, koi8-u, cp437, cp850, cp865, cp866 and cp866u. 16-line, 14-line and 8-line font data will be compiled in. Without this option, the syscons driver will use whatever font is already loaded in the video card, unless you explicitly load a software font at startup. See EXAMPLES below.

The following options will remove some features from the syscons driver and save kernel memory.

This option disables ``copy and paste'' operation in virtual terminals.
The syscons driver can load software fonts on some video cards. This option removes this feature. Note that if you still wish to use the mouse with this option then you must also use the SC_ALT_MOUSE_IMAGE option.
This option disables back-scrolling in virtual terminals.
This option removes mouse support in the syscons driver. The mouse daemon moused(8) will fail if this option is defined. This option implies the SC_NO_CUTPASTE option too.

The following driver flags can be used to control the syscons driver. They can be set either in the kernel configuration file (see config(8)), or else in the User Configuration Menu at boot time (see boot(8)).

0x0100 (AUTODETECT_KBD)
This option instructs the syscons driver to periodically scan for a keyboard device if it is not currently attached to one. Otherwise, the driver only probes for a keyboard once during bootup.

The following ioctl(2) commands are defined for the syscons driver in <sys/consio.h>.

int *mode
 
int *mode
Get or set the mode of the current (virtual) console. The mode can be one of:

same as KD_TEXT0
Text mode, restore fonts and palette
Graphics mode
Text mode, don't restore fonts and palette
Raster (pixel) text mode

int *color
Set the border color of the current (virtual) console.

scr_size_t *sizes
Set raster (pixel) text mode and adjust the current (virtual) console's geometry and font size. The scr_size_t argument structure is as follows: 
struct _scr_size {
	int	scr_size[3];
};

scrmap_t *map
 
scrmap_t *map
Get or set the screen map for the current (virtual) console. The scrmap_t argument structure is defined as follows: 
struct _scrmap {
	char	scrmap[256];
};

int *attr
Get the current text attribute.

int *color
Get the current text color.

int *type
Get the adapter type. This is equivalent to FBIO_ADPTYPE.

int *mode
Get the current video mode. This is equivalent to FBIO_GETMODE.

int *mode
Set the current video mode. This is equivalent to FBIO_SETMODE.

int *time
Set the screen saver blank interval (in seconds).

int *type
Set the text cursor shape. The argument type can be one or more of the following:

Set for a blinking cursor, unset for a non-blinking cursor.
Set for an underscore-shaped cursor, unset for a rectangle.

int *type
Set the bell type. The argument type is one or more of:

Set for a visual bell, unset for an audible bell.
Set to enable the bell, unset to disable it.

int *size
Set the history (scroll back) buffer size (in lines).

Clear the history (scroll back) buffer.

int *idle
Check if the (virtual) console has been idle.

int *mode
Set the screen saver mode. The argument mode can be one of:

Disable screen saver
Enable screen saver
Add a new screen saver

int *start
Start or stop the screen saver.

fnt8_t *font
 
fnt8_t *font
Get or set the 8x8 font. The fnt8_t argument structure is defined as follows: 
struct fnt8 {
	char	fnt8x8[8*256];
};

fnt14_t *font
 
fnt14_t *font
Get or set the 8x14 font. The fnt14_t argument structure is defined as follows: 
struct fnt14 {
	char	fnt8x14[14*256];
};

fnt16_t *font
 
fnt16_t *font
Get or set the 8x16 font. The fnt16_t argument structure is defined as follows: 
struct fnt16 {
	char	fnt8x16[16*256];
};

vid_info_t *info
Get information about the current video mode. The vid_info_t structure is defined as follows: 
struct vid_info {
	short		size;
	short		m_num;
	u_short		font_size;
	u_short		mv_row, mv_col;
	u_short		mv_rsz, mv_csz;
	struct colors	mv_norm,
			mv_rev,
			mv_grfc;
	u_char		mv_ovscan;
	u_char		mk_keylock;
};

int *version
Get the version of the driver.

int *adapter
Get the video adapter index. This is equivalent to FBIO_ADAPTER.

video_adapter_info_t *info
Get the video adapter information. This is equivalent to FBIO_ADPINFO.

video_info_t *info
Get the video mode information. This is equivalent to FBIO_MODEINFO.

video_info_t *info
Find a video mode. This is equivalent to FBIO_FINDMODE.

u_int *origin
Set the frame buffer window origin. This is equivalent to FBIO_SETWINORG.

int *kbd
Set a new keyboard.

Release the current keyboard.

scrshot_t *data
Make a snapshot of the current video buffer. The scrshot_t structure is defined as: 
struct scrshot {
	int		xsize;
	int		ysize;
	u_int16_t*	buf;
};

term_info_t *info
 
term_info_t *info
Get or set terminal characteristics. The term_info_t structure is defined as: 
struct term_info {
	int		ti_index;
	int		ti_flags;
	u_char		ti_name[TI_NAME_LEN];
	u_char		ti_desc[TI_DESC_LEN];
};

int *term
Get the next available terminal.

vtmode_t *mode
 
vtmode_t *mode
Get or set the terminal switching mode. The vtmode_t argument structure is defined as follows: 
struct vt_mode {
	char		mode;
	char		waitv;
	short		relsig;
	short		acqsig;
	short		frsig;
};

int *ack
Acknowledge the release or acquisition of a terminal. The ack argument can be one of:

The user refuses to release the screen, abort
The user has released the screen, go on
Acquisition of the screen acknowledged, switch completed

int *term
Activate the specified terminal.

int *term
Wait until the specified terminal is active.

int *term
Get the currently active terminal.

int *index
Get the index of the terminal.

int *lock
Prevent or permit terminal switching.

/dev/console
 
/dev/consolectl
 
/dev/ttyv?
virtual terminals
/etc/ttys
terminal initialization information
/usr/share/syscons/fonts/*
font files
/usr/share/syscons/keymaps/*
key map files
/usr/share/syscons/scrmaps/*
screen map files

As the syscons driver requires the keyboard driver and the video card driver, the kernel configuration file should contain the following lines.

device atkbdc0 at isa? port IO_KBD
device atkbd0 at atkbdc? irq 1
device vga0 at isa?
device sc0 at isa?
pseudo-device splash

If you do not intend to load the splash image or use the screen saver, the last line is not necessary, and can be omitted.

Note that the keyboard controller driver atkbdc is required by the keyboard driver atkbd.

The following lines will set the default colors. The normal text will be green on black background. The reversed text will be yellow on green background. Note that you cannot put any white space inside the quoted string, because of the current implementation of config(8).

options SC_NORM_ATTR=(FG_GREEN|BG_BLACK)
options SC_NORM_REV_ATTR=(FG_YELLOW|BG_GREEN)

The following lines will set the default colors of the kernel message. The kernel message will be printed bright red on black background. The reversed message will be black on red background.

options SC_KERNEL_CONS_ATTR=(FG_LIGHTRED|BG_BLACK)
options SC_KERNEL_CONS_REV_ATTR=(FG_BLACK|BG_RED)

The following line will set the default border color of the terminal. If the console is in framebuffer mode, or in raster (pixel) text mode, a thin green border will be visible around the terminal if the screen size is not an exact multiple of the font size. This border area can be much larger if the column or row count is explicitly specified (for example when using the kern.kms_columns tunable).

options SC_BORDER_COLOR=FG_GREEN

The following example adds the font files cp850-8x16.fnt, cp850-8x14.font and cp850-8x8.font to the kernel.

options SC_DFLT_FONT
makeoptions SC_DFLT_FONT=cp850
device sc0 at isa?

The amount of data that is possible to insert from the cut buffer is limited by the {MAX_INPUT}, a system limit on the number of bytes that may be stored in the terminal input queue - usually 1024 bytes (see termios(4)).

kbdcontrol(1), login(1), vidcontrol(1), atkbd(4), atkbdc(4), keyboard(4), screen(4), splash(4), sysmouse(4), ukbd(4), vga(4), kbdmap(5), rc.conf(5), ttys(5), config(8), getty(8), kldload(8), moused(8)

The syscons driver first appeared in FreeBSD 1.0.

The syscons driver was written by Søren Schmidt <sos@FreeBSD.org>. This manual page was written by Kazutaka Yokota <yokota@FreeBSD.org> and Sascha Wildner.

This manual page is incomplete and needs revision.

June 4, 2018 DragonFly-5.6.1