man/man4/syscons.4

.\"
.\" Copyright (c) 1999
.\" Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp>
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.Dd May 25, 2022
.Dt SYSCONS 4
.Os
.Sh NAME
.Nm syscons ,
.Nm sc
.Nd the legacy console driver
.Sh SYNOPSIS
.Cd "options MAXCONS=N"
.Cd "options SC_ALT_MOUSE_IMAGE"
.Cd "options SC_CUT_SEPCHARS=_characters_"
.Cd "options SC_CUT_SPACES2TABS"
.Cd "options SC_DFLT_TERM"
.Cd "options SC_DISABLE_KDBKEY"
.Cd "options SC_DISABLE_REBOOT"
.Cd "options SC_HISTORY_SIZE=N"
.Cd "options SC_MOUSE_CHAR=C"
.Cd "options SC_NO_CUTPASTE"
.Cd "options SC_NO_FONT_LOADING"
.Cd "options SC_NO_HISTORY"
.Cd "options SC_NO_PALETTE_LOADING"
.Cd "options SC_NO_SUSPEND_VTYSWITCH"
.Cd "options SC_NO_SYSMOUSE"
.Cd "options SC_NO_TERM_DUMB"
.Cd "options SC_NO_TERM_SC"
.Cd "options SC_NO_TERM_SCTEKEN"
.Cd "options SC_PIXEL_MODE"
.Cd "options SC_TWOBUTTON_MOUSE"
.Cd "options SC_NORM_ATTR=_attribute_"
.Cd "options SC_NORM_REV_ATTR=_attribute_"
.Cd "options SC_KERNEL_CONS_ATTR=_attribute_"
.Cd "options SC_KERNEL_CONS_ATTRS=_attributes_"
.Cd "options SC_KERNEL_CONS_REV_ATTR=_attribute_"
.Cd "options SC_DFLT_FONT"
.Cd "makeoptions SC_DFLT_FONT=_font_name_"
.Cd "device sc"
.Pp
In
.Pa /boot/device.hints :
.Cd hint.sc.0.at="isa"
.Cd hint.sc.0.vesa_mode=0x103
.Pp
In
.Pa /boot/loader.conf :
.Cd kern.vty=sc
.Sh DESCRIPTION
The
.Nm
driver provides multiple virtual terminals.
It resembles the SCO color console driver.
.Pp
Note that the
.Nm
driver is not compatible with systems booted via
.Xr UEFI 8 .
Forcing use of
.Nm
on such systems will result in no usable console.
.Pp
The
.Nm
driver is implemented on top of the keyboard driver
.Pq Xr atkbd 4
and the video card driver
.Pq Xr vga 4
and so requires both of them to be configured in the system.
.Pp
There can be only one
.Nm
device defined in the system.
.Ss Virtual Terminals
The
.Nm
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.
.Pp
In order to use virtual terminals, they must be individually
marked ``on'' in
.Pa /etc/ttys
so that
.Xr getty 8
will recognize them to be active and run
.Xr login 1
to let the user log in to the system.
By default, only the first eight virtual terminals are activated in
.Pa /etc/ttys .
.Pp
You press the
.Dv 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.
.Bd -literal -offset indent
Alt-F1   ttyv0      Alt-F7   ttyv6      Shift-Alt-F1   ttyva
Alt-F2   ttyv1      Alt-F8   ttyv7      Shift-Alt-F2   ttyvb
Alt-F3   ttyv2      Alt-F9   ttyv8      Shift-Alt-F3   ttyvc
Alt-F4   ttyv3      Alt-F10  ttyv9      Shift-Alt-F4   ttyvd
Alt-F5   ttyv4      Alt-F11  ttyva      Shift-Alt-F5   ttyve
Alt-F6   ttyv5      Alt-F12  ttyvb      Shift-Alt-F6   ttyvf
.Ed
.Pp
You can also use the ``nscr'' key (usually the
.Dv PrintScreen
key on the AT Enhanced keyboard) to cycle available virtual terminals.
.Pp
The default number of available virtual terminals is 16.
This can be changed with the kernel configuration option
.Dv MAXCONS
(see below).
.Pp
Note that the X server usually requires a virtual terminal for display
purposes, so at least one terminal must be left unused by
.Xr getty 8
so that it can be used by the X server.
.Ss Key Definitions and Function Key Strings
The
.Nm
driver, in conjunction with the keyboard driver, allows the user
to change key definitions and function key strings.
The
.Xr 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
.Xr keyboard 4
and
.Xr kbdmap 5
for the keymap file.
.Pp
You may want to set the
.Ar keymap
variable in
.Pa /etc/rc.conf.local
to the desired keymap file so that it will be automatically loaded
when the system starts up.
.Ss Software Font
For most modern video cards, e.g., VGA, the
.Nm
driver and the video card driver allow the user to change
the font used on the screen.
The
.Xr vidcontrol 1
command can be used to load a font file from
.Pa /usr/share/syscons/fonts .
.Pp
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.
.Pp
You may set
.Ar font8x8 ,
.Ar font8x14
and
.Ar font8x16
variables in
.Pa /etc/rc.conf
to the desired font files so that they will be automatically loaded
when the system starts up.
.Pp
Optionally you can specify a particular font file as the default.
See the
.Dv SC_DFLT_FONT
option below.
.Ss 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
.Xr vidcontrol 1
to load a screen map file which defines the mapping between character codes.
.Ss 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
.Xr moused 8
and enable the mouse cursor in the virtual terminal via
.Xr vidcontrol 1 .
.Pp
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.
.Pp
If your mouse has only two buttons, you may want to use the
.Dv 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
.Xr moused 8
for more details.
.Ss Back Scrolling
The
.Nm
driver allows the user to browse the output which has ``scrolled off''
the top of the screen.
.Pp
Press the ``slock'' key (usually
.Dv ScrllLock
/
.Dv Scroll Lock
or
.Dv Pause
on many keyboards) and the terminal is
in the ``scrollback'' mode.
It is indicated by the
.Dv Scroll Lock
LED.
Use the arrow keys, the
.Dv Page Up/Down
keys and the
.Dv Home/End
keys to scroll buffered terminal output.
Press the ``slock'' key again to get back to the normal terminal mode.
.Pp
The size of the scrollback buffer can be set by the
.Dv SC_HISTORY_SIZE
option described below.
.Ss Screen Saver
The
.Nm
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
.Xr splash 4
and
.Xr vidcontrol 1
for more details.
.Sh DRIVER CONFIGURATION
.Ss Kernel Configuration Options
The following kernel configuration options control the
.Nm
driver.
.Bl -tag -width MOUSE
.It Dv MAXCONS=N
This option sets the number of virtual terminals to
.Fa N .
The default value is 16.
.It Dv 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
.Dv SC_NO_FONT_LOADING
option then you must also use this option if you wish to be able to use
the mouse.
.It Dv 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
.Qq Li \ex20
\(em a space character.
.It Dv 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.
.It Dv SC_DFLT_TERM=_name_
This option specifies the name of the preferred terminal emulator.
.It Dv SC_DISABLE_KDBKEY
This option disables the ``debug'' key combination (by default, it is
.Dv Alt-Esc ,
or
.Dv 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.
If this option is not defined, this behavior may be controlled at runtime
by the
.Xr sysctl 8
variable
.Va hw.syscons.kbd_debug .
.It Dv SC_DISABLE_REBOOT
This option disables the ``reboot'' key (by default, it is
.Dv Ctl-Alt-Del ) ,
so that the casual user may not accidentally reboot the system.
If this option is not defined, this behavior may be controlled at runtime
by the
.Xr sysctl 8
variable
.Va hw.syscons.kbd_reboot .
.It Dv SC_HISTORY_SIZE=N
Sets the size of back scroll buffer to
.Fa N
lines.
The default value is 100.
.It Dv SC_MOUSE_CHAR=C
Unless the
.Dv SC_ALT_MOUSE_IMAGE
option above is specified, the
.Nm
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
.Fa C
to be used for this purpose.
The default value is 0xd0.
A good candidate is 0x03.
.It Dv 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
.Dv VESAMODE
flag below.
.It Dv 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
.Sx Mouse Support and Copy-and-Paste
above.
.It Dv SC_NORM_ATTR=_attribute_
.It Dv SC_NORM_REV_ATTR=_attribute_
.It Dv SC_KERNEL_CONS_ATTR=_attribute_
.It Dv SC_KERNEL_CONS_ATTRS=_attributes_
.It Dv SC_KERNEL_CONS_REV_ATTR=_attribute_
These options will set the default colors.
Available colors are defined in
.In machine/pc/display.h .
See
.Sx EXAMPLES
below.
.Dv SC_KERNEL_CONS_ATTRS
is a character string giving a sequence of attributes in binary format.
The sequence will be repeated up to the number of CPUs.
Beware that the string must not be null,
since the kernel divides by its length.
.It Dv 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
.Nm
driver will use whatever font is already loaded in the video card,
unless you explicitly load a software font at startup.
See
.Sx EXAMPLES
below.
.It Dv SC_NO_SUSPEND_VTYSWITCH
This option, which is also available as
.Xr loader 8
tunable and
.Xr sysctl 8
variable
.Va 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.
.El
.Pp
The following options will remove some features from the
.Nm
driver and save kernel memory.
.Bl -tag -width MOUSE
.It Dv SC_NO_CUTPASTE
This option disables ``copy and paste'' operation in virtual
terminals.
.It Dv SC_NO_FONT_LOADING
The
.Nm
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
.Dv SC_ALT_MOUSE_IMAGE
option.
.It Dv SC_NO_HISTORY
This option disables back-scrolling in virtual terminals.
.\".It Dv SC_NO_PALETTE_LOADING
.It Dv SC_NO_SYSMOUSE
This option removes mouse support in the
.Nm
driver.
The mouse daemon
.Xr moused 8
will fail if this option is defined.
This option implies the
.Dv SC_NO_CUTPASTE
option too.
.It Dv SC_NO_TERM_DUMB
.It Dv SC_NO_TERM_SC
.It Dv SC_NO_TERM_SCTEKEN
These options remove the
.Qq dumb ,
.Qq sc ,
and
.Qq scteken
terminal emulators, respectively.
.El
.Ss Driver Flags
The following driver flags can be used to control the
.Nm
driver.
Driver flags can be set with the
.Cd hint.sc.0.flags
tunable, either in
.Pa /boot/device.hints ,
or else at the loader prompt (see
.Xr loader 8 ) .
.Bl -tag -width bit_0
.\".It bit 0 (VISUAL_BELL)
.\"Uses the ``visual'' bell.
.\"The screen will blink instead of generating audible sound.
.\".It bit 1,2 (CURSOR_TYPE)
.\"This option specifies the cursor appearance.
.\"Possible values are:
.\".Bl -tag -width TYPE -compact
.\".It Dv 0
.\"normal block cursor
.\".It Dv 2
.\"blinking block cursor
.\".It Dv 4
.\"underline cursor
.\".It Dv 6
.\"blinking underline (aka destructive) cursor
.\".El
.\".It bit 6 (QUIET_BELL)
.\"This option suppresses the bell, whether audible or visual,
.\"if it is rung in a background virtual terminal.
.It 0x0080 (VESAMODE)
This option puts the video card in the VESA mode specified by
.Pa /boot/device.hints
variable
.Va vesa_mode
during kernel initialization.
Note that in order for this flag to work, the kernel must be
compiled with the
.Dv SC_PIXEL_MODE
option explained above.
A list of the available mode can be obtained via
.Xr vidcontrol 1 .
.\"Note also that the ``copy-and-paste'' function is not currently supported
.\"in this mode and the mouse pointer will not be displayed.
.It 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.
.El
.Ss 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 kern.vty
When both
.Nm
and
.Xr vt 4
have been compiled into the kernel, the one to use for the system console can
be selected by setting this variable to
.Ql sc
or
.Ql vt .
The
.Pa GENERIC
kernel uses
.Xr vt 4
when this value is not set.
.El
.Sh FILES
.Bl -tag -width /usr/share/syscons/xxxxyyyyzzz -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/syscons/fonts/*
font files
.It Pa /usr/share/syscons/keymaps/*
key map files
.It Pa /usr/share/syscons/scrmaps/*
screen map files
.El
.Sh EXAMPLES
As the
.Nm
driver requires the keyboard driver and the video card driver,
the kernel configuration file should contain the following lines.
.Bd -literal -offset indent
device atkbdc
device atkbd
device vga
device sc
device splash
.Ed
.Pp
You also need the following lines in
.Pa /boot/device.hints
for these drivers.
.Bd -literal -offset indent
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"
.Ed
.Pp
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.
.Pp
Note that the keyboard controller driver
.Nm atkbdc
is required by the keyboard driver
.Nm atkbd .
.Pp
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
.Xr config 8 .
.Pp
.Dl "options SC_NORM_ATTR=(FG_GREEN|BG_BLACK)"
.Dl "options SC_NORM_REV_ATTR=(FG_YELLOW|BG_GREEN)"
.Pp
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.
.Pp
.Dl "options SC_KERNEL_CONS_ATTR=(FG_LIGHTRED|BG_BLACK)"
.Dl "options SC_KERNEL_CONS_REV_ATTR=(FG_BLACK|BG_RED)"
.Pp
Provided
.Dv SC_KERNEL_CONS_ATTR
is not set, or is set to its default of bright white on black,
the following line will set 4 red-ish colors
for printing kernel messages in colors depending on the CPU.
.Pp
.Dl options SC_KERNEL_CONS_ATTRS=\e"\ex0c\ex04\ex40\ex0e\e"
.Pp
The default scheme is probably better for up to 8 CPUs.
Use a long string to get unique colors for more than 8 CPUs.
.Pp
To turn off all per-CPU coloring of kernel messages,
set SC_KERNEL_CONS_ATTR to a non-default value,
or use the default in a pattern of length 1.
.Pp
.Dl options SC_KERNEL_CONS_ATTRS=\e"\ex0f\e"
.Pp
The following example adds the font files
.Pa cp850-8x16.fnt ,
.Pa cp850-8x14.font
and
.Pa cp850-8x8.font
to the kernel.
.Pp
.Dl "options SC_DFLT_FONT"
.Dl "makeoptions SC_DFLT_FONT=cp850"
.Dl "device sc"
.\".Sh DIAGNOSTICS
.Sh SEE ALSO
.Xr kbdcontrol 1 ,
.Xr login 1 ,
.Xr vidcontrol 1 ,
.Xr atkbd 4 ,
.Xr atkbdc 4 ,
.Xr keyboard 4 ,
.Xr screen 4 ,
.Xr splash 4 ,
.Xr ukbd 4 ,
.Xr vga 4 ,
.Xr vt 4 ,
.Xr kbdmap 5 ,
.Xr rc.conf 5 ,
.Xr ttys 5 ,
.Xr config 8 ,
.Xr getty 8 ,
.Xr kldload 8 ,
.Xr moused 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 1.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An S\(/oren Schmidt Aq Mt sos@FreeBSD.org .
This manual page was written by
.An Kazutaka Yokota Aq Mt yokota@FreeBSD.org .
.Sh 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
.Xr termios 4 ) .
.Sh BUGS
This manual page is incomplete and urgently needs revision.