SYSCONS (4) | Special files and drivers | Unix Manual Pages

SYSCONS (4) | Special files and drivers | Unix Manual Pages | :man▋

The syscons driver is implemented on top of the keyboard driver (atkbd(4)) and the video card driver (vga(4)) and so requires both of them to be configured in the system.

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

Virtual Terminals

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 ttyv10Shift-Alt-F5 ttyv14
Alt-F6 ttyv5 Alt-F12 ttyv11Shift-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.

Key Definitions and Function Key Strings

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.

Software Font

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.

Screen Map

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.

Mouse Support and Copy-and-Paste

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.

Back Scrolling

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.

Screen Saver

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.

DRIVER CONFIGURATION

Kernel Configuration Options

The following kernel configuration options control the syscons driver.

`MAXCONS=N`
	This option sets the number of virtual terminals to N. The default value is 16.
`SC_ALT_MOUSE_IMAGE`
	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.
`SC_CUT_SEPCHARS=_characters_`
	This options specifies characters that will be looked for when the driver searches for words boundaries when doing cut operation. By default, its value is "\x20" — a space character.
`SC_CUT_SPACES2TABS`
	This options instructs the driver to convert leading spaces into tabs when copying data into cut buffer. This might be useful to preserve indentation when copying tab-indented text.
`SC_DISABLE_KDBKEY`
	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 (KDB) by pressing the key combination. KDB will still be invoked when the kernel panics or hits a break point if it is included in the kernel.
`SC_DISABLE_REBOOT`
	This option disables the ‘‘reboot’’ key (by default, it is `Ctl-Alt-Del`), so that the casual user may not accidentally reboot the system.
`SC_HISTORY_SIZE=N`
	Sets the size of back scroll buffer to N lines. The default value is 100.
`SC_MOUSE_CHAR=C`
	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.
`SC_PIXEL_MODE`
	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. See the `VESA800X600` flag below.
`SC_TWOBUTTON_MOUSE`
	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.
`SC_NORM_ATTR=_attribute_` `SC_NORM_REV_ATTR=_attribute_` `SC_KERNEL_CONS_ATTR=_attribute_` `SC_KERNEL_CONS_REV_ATTR=_attribute_`
	These options will set the default colors. Available colors are defined in .In machine/pc/display.h . See EXAMPLES below.
`SC_DFLT_FONT`
	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.
`SC_NO_SUSPEND_VTYSWITCH`
	This option, which is also available as loader(8) tunable and sysctl(8) variable (hw.syscons.sc_no_suspend_vtswitch), disables switching between virtual terminals (graphics <-> text) during suspend/resume (ACPI and APM). Use this option if your system is freezing when you are running X and trying to suspend.

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

`SC_NO_CUTPASTE`
	This option disables ‘‘copy and paste’’ operation in virtual terminals.
`SC_NO_FONT_LOADING`
	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.
`SC_NO_HISTORY`
	This option disables back-scrolling in virtual terminals.
`SC_NO_SYSMOUSE`
	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.

Driver Flags

The following driver flags can be used to control the syscons driver. They can be set either in /boot/device.hints, or else at the loader prompt (see loader(8)).

0x0080 (VESA800X600)
	This option puts the video card in the VESA 800x600 pixel, 16 color mode. It may be useful for laptop computers for which the 800x600 mode is otherwise unsupported by the X server. Note that in order for this flag to work, the kernel must be compiled with the `SC_PIXEL_MODE` option explained above.
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.

FILES

`/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

EXAMPLES

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

device atkbdc
device atkbd
device vga
device sc

device splash

You also need the following lines in /boot/device.hints for these drivers.
hint.atkbdc.0.at="isa"
hint.atkbdc.0.port="0x060"
hint.atkbd.0.at="atkbdc"
hint.atkbd.0.irq="1"
hint.vga.0.at="isa"
hint.sc.0.at="isa"

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 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 sc"

CAVEATS

The amount of data that is possible to insert from the cut buffer is limited by the
.Brq Dv 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)).

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Created by Blin Media, 2008-2013

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