path: root/man2/ioctl_console.2

'\" t
.\" Copyright (c) 1995 Jim Van Zandt <jrv@vanzandt.mv.com> and aeb
.\" Sun Feb 26 11:46:23 MET 1995
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.\" Modified, Sun Feb 26 15:04:20 1995, faith@cs.unc.edu
.\" Modified, Thu Apr 20 22:08:17 1995, jrv@vanzandt.mv.com
.\" Modified, Mon Sep 18 22:32:47 1995, hpa@storm.net (H. Peter Anvin)
.\" FIXME The following are not documented:
.\"     KDFONTOP (since Linux 2.1.111)
.\"     KDGKBDIACRUC (since Linux 2.6.24)
.\"     KDSKBDIACR
.\"     KDSKBDIACRUC (since Linux 2.6.24)
.\"     KDKBDREP (since Linux 2.1.113)
.\"     KDMAPDISP (not implemented as at Linux 2.6.27)
.\"     KDUNMAPDISP (not implemented as at Linux 2.6.27)
.\"     VT_LOCKSWITCH (since Linux 1.3.47, needs CAP_SYS_TTY_CONFIG)
.\"     VT_UNLOCKSWITCH (since Linux 1.3.47, needs CAP_SYS_TTY_CONFIG)
.\"     VT_GETHIFONTMASK (since Linux 2.6.18)
.\"
.TH ioctl_console 2 2024-03-03 "Linux man-pages 6.7"
.SH NAME
ioctl_console \- ioctls for console terminal and virtual consoles
.SH DESCRIPTION
The following Linux-specific
.BR ioctl (2)
operations are supported for console terminals and virtual consoles.
Each operation requires a third argument, assumed here to be
.IR argp .
.TP
.B KDGETLED
Get state of LEDs.
.I argp
points to a
.IR char .
The lower three bits
of
.I *argp
are set to the state of the LEDs, as follows:
.TS
l l l.
LED_CAP 	0x04	caps lock led
LED_NUM 	0x02	num lock led
LED_SCR 	0x01	scroll lock led
.TE
.TP
.B KDSETLED
Set the LEDs.
The LEDs are set to correspond to the lower three bits of the
unsigned long integer in
.IR argp .
However, if a higher order bit is set,
the LEDs revert to normal: displaying the state of the
keyboard functions of caps lock, num lock, and scroll lock.
.P
Before Linux 1.1.54, the LEDs just reflected the state of the corresponding
keyboard flags, and KDGETLED/KDSETLED would also change the keyboard
flags.
Since Linux 1.1.54 the LEDs can be made to display arbitrary
information, but by default they display the keyboard flags.
The following two ioctls are used to access the keyboard flags.
.TP
.B KDGKBLED
Get keyboard flags CapsLock, NumLock, ScrollLock (not lights).
.I argp
points to a char which is set to the flag state.
The low order three bits (mask 0x7) get the current flag state,
and the low order bits of the next nibble (mask 0x70) get
the default flag state.
(Since Linux 1.1.54.)
.TP
.B KDSKBLED
Set keyboard flags CapsLock, NumLock, ScrollLock (not lights).
.I argp
is an unsigned long integer that has the desired flag state.
The low order three bits (mask 0x7) have the flag state,
and the low order bits of the next nibble (mask 0x70) have
the default flag state.
(Since Linux 1.1.54.)
.TP
.B KDGKBTYPE
Get keyboard type.
This returns the value KB_101, defined as 0x02.
.TP
.B KDADDIO
Add I/O port as valid.
Equivalent to
.IR ioperm(arg,1,1) .
.TP
.B KDDELIO
Delete I/O port as valid.
Equivalent to
.IR ioperm(arg,1,0) .
.TP
.B KDENABIO
Enable I/O to video board.
Equivalent to
.IR "ioperm(0x3b4, 0x3df\-0x3b4+1, 1)" .
.TP
.B KDDISABIO
Disable I/O to video board.
Equivalent to
.IR "ioperm(0x3b4, 0x3df\-0x3b4+1, 0)" .
.TP
.B KDSETMODE
Set text/graphics mode.
.I argp
is an unsigned integer containing one of:
.TS
l l.
KD_TEXT	0x00
KD_GRAPHICS	0x01
.TE
.TP
.B KDGETMODE
Get text/graphics mode.
.I argp
points to an
.I int
which is set to one
of the values shown above for
.BR KDSETMODE .
.TP
.B KDMKTONE
Generate tone of specified length.
The lower 16 bits of the unsigned long integer in
.I argp
specify the period in clock cycles,
and the upper 16 bits give the duration in msec.
If the duration is zero, the sound is turned off.
Control returns immediately.
For example,
.I argp
= (125<<16) + 0x637 would specify
the beep normally associated with a ctrl-G.
(Thus since Linux 0.99pl1; broken in Linux 2.1.49-50.)
.TP
.B KIOCSOUND
Start or stop sound generation.
The lower 16 bits of
.I argp
specify the period in clock cycles
(that is,
.I argp
= 1193180/frequency).
.I argp
= 0 turns sound off.
In either case, control returns immediately.
.TP
.B GIO_CMAP
Get the current default color map from kernel.
.I argp
points to
a 48-byte array.
(Since Linux 1.3.3.)
.TP
.B PIO_CMAP
Change the default text-mode color map.
.I argp
points to a
48-byte array which contains, in order, the Red, Green, and Blue
values for the 16 available screen colors: 0 is off, and 255 is full
intensity.
The default colors are, in order: black, dark red, dark
green, brown, dark blue, dark purple, dark cyan, light grey, dark
grey, bright red, bright green, yellow, bright blue, bright purple,
bright cyan, and white.
(Since Linux 1.3.3.)
.TP
.B GIO_FONT
Gets 256-character screen font in expanded form.
.I argp
points to an 8192-byte array.
Fails with error code
.B EINVAL
if the
currently loaded font is a 512-character font, or if the console is
not in text mode.
.TP
.B GIO_FONTX
Gets screen font and associated information.
.I argp
points to a
.I "struct consolefontdesc"
(see
.BR PIO_FONTX ).
On call, the
.I charcount
field should be set to the maximum number of
characters that would fit in the buffer pointed to by
.IR chardata .
On return, the
.I charcount
and
.I charheight
are filled with
the respective data for the currently loaded font, and the
.I chardata
array contains the font data if the initial value of
.I charcount
indicated enough space was available; otherwise the
buffer is untouched and
.I errno
is set to
.BR ENOMEM .
(Since Linux 1.3.1.)
.TP
.B PIO_FONT
Sets 256-character screen font.
Load font into the EGA/VGA character
generator.
.I argp
points to an 8192-byte map, with 32 bytes per
character.
Only the first
.I N
of them are used for an 8x\fIN\fP font
(0 <
.I N
<= 32).
This call also invalidates the Unicode mapping.
.TP
.B PIO_FONTX
Sets screen font and associated rendering information.
.I argp
points to a
.IP
.in +4n
.EX
struct consolefontdesc {
    unsigned short charcount;  /* characters in font
                                  (256 or 512) */
    unsigned short charheight; /* scan lines per
                                  character (1\-32) */
    char          *chardata;   /* font data in
                                  expanded form */
};
.EE
.in
.IP
If necessary, the screen will be appropriately resized, and
.B SIGWINCH
sent to the appropriate processes.
This call also invalidates the Unicode mapping.
(Since Linux 1.3.1.)
.TP
.B PIO_FONTRESET
Resets the screen font, size, and Unicode mapping to the bootup
defaults.
.I argp
is unused, but should be set to NULL to
ensure compatibility with future versions of Linux.
(Since Linux 1.3.28.)
.TP
.B GIO_SCRNMAP
Get screen mapping from kernel.
.I argp
points to an area of size
E_TABSZ, which is loaded with the font positions used to display each
character.
This call is likely to return useless information if the
currently loaded font is more than 256 characters.
.TP
.B GIO_UNISCRNMAP
Get full Unicode screen mapping from kernel.
.I argp
points to an
area of size
.IR "E_TABSZ*sizeof(unsigned short)" ,
which is loaded with the
Unicodes each character represent.
A special set of Unicodes,
starting at U+F000, are used to represent "direct to font" mappings.
(Since Linux 1.3.1.)
.TP
.B PIO_SCRNMAP
Loads the "user definable" (fourth) table in the kernel which maps
bytes into console screen symbols.
.I argp
points to an area of
size E_TABSZ.
.TP
.B PIO_UNISCRNMAP
Loads the "user definable" (fourth) table in the kernel which maps
bytes into Unicodes, which are then translated into screen symbols
according to the currently loaded Unicode-to-font map.
Special Unicodes starting at U+F000 can be used to map directly to the font
symbols.
(Since Linux 1.3.1.)
.TP
.B GIO_UNIMAP
Get Unicode-to-font mapping from kernel.
.I argp
points to a
.IP
.in +4n
.EX
struct unimapdesc {
    unsigned short  entry_ct;
    struct unipair *entries;
};
.EE
.in
.IP
where
.I entries
points to an array of
.IP
.in +4n
.EX
struct unipair {
    unsigned short unicode;
    unsigned short fontpos;
};
.EE
.in
.IP
(Since Linux 1.1.92.)
.TP
.B PIO_UNIMAP
Put unicode-to-font mapping in kernel.
.I argp
points to a
.IR "struct unimapdesc" .
(Since Linux 1.1.92)
.TP
.B PIO_UNIMAPCLR
Clear table, possibly advise hash algorithm.
.I argp
points to a
.IP
.in +4n
.EX
struct unimapinit {
    unsigned short advised_hashsize;  /* 0 if no opinion */
    unsigned short advised_hashstep;  /* 0 if no opinion */
    unsigned short advised_hashlevel; /* 0 if no opinion */
};
.EE
.in
.IP
(Since Linux 1.1.92.)
.TP
.B KDGKBMODE
Gets current keyboard mode.
.I argp
points to a
.I long
which is set to one
of these:
.TS
l l.
K_RAW	0x00  /* Raw (scancode) mode */
K_XLATE	0x01  /* Translate keycodes using keymap */
K_MEDIUMRAW	0x02  /* Medium raw (scancode) mode */
K_UNICODE	0x03  /* Unicode mode */
K_OFF	0x04  /* Disabled mode; since Linux 2.6.39 */
.\" K_OFF: commit 9fc3de9c83565fcaa23df74c2fc414bb6e7efb0a
.TE
.TP
.B KDSKBMODE
Sets current keyboard mode.
.I argp
is a
.I long
equal to one of the values shown for
.BR KDGKBMODE .
.TP
.B KDGKBMETA
Gets meta key handling mode.
.I argp
points to a
.I long
which is
set to one of these:
.TS
l l l.
K_METABIT	0x03	set high order bit
K_ESCPREFIX	0x04	escape prefix
.TE
.TP
.B KDSKBMETA
Sets meta key handling mode.
.I argp
is a
.I long
equal to one of the values shown above for
.BR KDGKBMETA .
.TP
.B KDGKBENT
Gets one entry in key translation table (keycode to action code).
.I argp
points to a
.IP
.in +4n
.EX
struct kbentry {
    unsigned char  kb_table;
    unsigned char  kb_index;
    unsigned short kb_value;
};
.EE
.in
.IP
with the first two members filled in:
.I kb_table
selects the key table (0 <=
.I kb_table
< MAX_NR_KEYMAPS),
and
.I kb_index
is the keycode (0 <=
.I kb_index
< NR_KEYS).
.I kb_value
is set to the corresponding action code,
or K_HOLE if there is no such key,
or K_NOSUCHMAP if
.I kb_table
is invalid.
.TP
.B KDSKBENT
Sets one entry in translation table.
.I argp
points to a
.IR "struct kbentry" .
.TP
.B KDGKBSENT
Gets one function key string.
.I argp
points to a
.IP
.in +4n
.EX
struct kbsentry {
    unsigned char kb_func;
    unsigned char kb_string[512];
};
.EE
.in
.IP
.I kb_string
is set to the (null-terminated) string corresponding to
the
.IR kb_func th
function key action code.
.TP
.B KDSKBSENT
Sets one function key string entry.
.I argp
points to a
.IR "struct kbsentry" .
.TP
.B KDGKBDIACR
Read kernel accent table.
.I argp
points to a
.IP
.in +4n
.EX
struct kbdiacrs {
    unsigned int   kb_cnt;
    struct kbdiacr kbdiacr[256];
};
.EE
.in
.IP
where
.I kb_cnt
is the number of entries in the array, each of which
is a
.IP
.in +4n
.EX
struct kbdiacr {
    unsigned char diacr;
    unsigned char base;
    unsigned char result;
};
.EE
.in
.TP
.B KDGETKEYCODE
Read kernel keycode table entry (scan code to keycode).
.I argp
points to a
.IP
.in +4n
.EX
struct kbkeycode {
    unsigned int scancode;
    unsigned int keycode;
};
.EE
.in
.IP
.I keycode
is set to correspond to the given
.IR scancode .
(89 <=
.I scancode
<= 255 only.
For 1 <=
.I scancode
<= 88,
.IR keycode == scancode .)
(Since Linux 1.1.63.)
.TP
.B KDSETKEYCODE
Write kernel keycode table entry.
.I argp
points to a
.IR "struct kbkeycode" .
(Since Linux 1.1.63.)
.TP
.B KDSIGACCEPT
The calling process indicates its willingness to accept the signal
.I argp
when it is generated by pressing an appropriate key combination.
(1 <=
.I argp
<= NSIG).
(See
.IR spawn_console ()
in
.IR linux/drivers/char/keyboard.c .)
.TP
.B VT_OPENQRY
Returns the first available (non-opened) console.
.I argp
points to an
.I int
which is set to the
number of the vt (1 <=
.I *argp
<= MAX_NR_CONSOLES).
.TP
.B VT_GETMODE
Get mode of active vt.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_mode {
    char  mode;    /* vt mode */
    char  waitv;   /* if set, hang on writes if not active */
    short relsig;  /* signal to raise on release op */
    short acqsig;  /* signal to raise on acquisition */
    short frsig;   /* unused (set to 0) */
};
.EE
.in
.IP
which is set to the mode of the active vt.
.I mode
is set to one of these values:
.TS
l l.
VT_AUTO	auto vt switching
VT_PROCESS	process controls switching
VT_ACKACQ	acknowledge switch
.TE
.TP
.B VT_SETMODE
Set mode of active vt.
.I argp
points to a
.IR "struct vt_mode" .
.TP
.B VT_GETSTATE
Get global vt state info.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_stat {
    unsigned short v_active;  /* active vt */
    unsigned short v_signal;  /* signal to send */
    unsigned short v_state;   /* vt bit mask */
};
.EE
.in
.IP
For each vt in use, the corresponding bit in the
.I v_state
member is set.
(Linux 1.0 through Linux 1.1.92.)
.TP
.B VT_RELDISP
Release a display.
.TP
.B VT_ACTIVATE
Switch to vt
.I argp
(1 <=
.I argp
<= MAX_NR_CONSOLES).
.TP
.B VT_WAITACTIVE
Wait until vt
.I argp
has been activated.
.TP
.B VT_DISALLOCATE
Deallocate the memory associated with vt
.IR argp .
(Since Linux 1.1.54.)
.TP
.B VT_RESIZE
Set the kernel's idea of screensize.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_sizes {
    unsigned short v_rows;       /* # rows */
    unsigned short v_cols;       /* # columns */
    unsigned short v_scrollsize; /* no longer used */
};
.EE
.in
.IP
Note that this does not change the videomode.
See
.BR resizecons (8).
(Since Linux 1.1.54.)
.TP
.B VT_RESIZEX
Set the kernel's idea of various screen parameters.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_consize {
    unsigned short v_rows;  /* number of rows */
    unsigned short v_cols;  /* number of columns */
    unsigned short v_vlin;  /* number of pixel rows
                               on screen */
    unsigned short v_clin;  /* number of pixel rows
                               per character */
    unsigned short v_vcol;  /* number of pixel columns
                               on screen */
    unsigned short v_ccol;  /* number of pixel columns
                               per character */
};
.EE
.in
.IP
Any parameter may be set to zero, indicating "no change", but if
multiple parameters are set, they must be self-consistent.
Note that this does not change the videomode.
See
.BR resizecons (8).
(Since Linux 1.3.3.)
.P
The action of the following ioctls depends on the first byte in the struct
pointed to by
.IR argp ,
referred to here as the
.IR subcode .
These are legal only for the superuser or the owner of the current terminal.
Symbolic
.IR subcode s
are available in
.I <linux/tiocl.h>
since
Linux 2.5.71.
.TP
.BR TIOCLINUX ", " subcode = 0
Dump the screen.
Disappeared in Linux 1.1.92.
(With Linux 1.1.92 or later, read from
.I /dev/vcsN
or
.I /dev/vcsaN
instead.)
.TP
.BR TIOCLINUX ", " subcode = 1
Get task information.
Disappeared in Linux 1.1.92.
.TP
.BR TIOCLINUX ", " subcode = TIOCL_SETSEL
Set selection.
.I argp
points to a
.IP
.in +4n
.EX
struct {
    char  subcode;
    short xs, ys, xe, ye;
    short sel_mode;
};
.EE
.in
.IP
.I xs
and
.I ys
are the starting column and row.
.I xe
and
.I ye
are the ending
column and row.
(Upper left corner is row=column=1.)
.I sel_mode
is 0 for character-by-character selection,
1 for word-by-word selection,
or 2 for line-by-line selection.
The indicated screen characters are highlighted and saved
in a kernel buffer.
.IP
Since Linux 6.7, using this subcode requires the
.B CAP_SYS_ADMIN
capability.
.TP
.BR TIOCLINUX ", " subcode = TIOCL_PASTESEL
Paste selection.
The characters in the selection buffer are
written to
.IR fd .
.IP
Since Linux 6.7, using this subcode requires the
.B CAP_SYS_ADMIN
capability.
.TP
.BR TIOCLINUX ", " subcode = TIOCL_UNBLANKSCREEN
Unblank the screen.
.TP
.BR TIOCLINUX ", " subcode = TIOCL_SELLOADLUT
Sets contents of a 256-bit look up table defining characters in a "word",
for word-by-word selection.
(Since Linux 1.1.32.)
.IP
Since Linux 6.7, using this subcode requires the
.B CAP_SYS_ADMIN
capability.
.TP
.BR TIOCLINUX ", " subcode = TIOCL_GETSHIFTSTATE
.I argp
points to a char which is set to the value of the kernel
variable
.IR shift_state .
(Since Linux 1.1.32.)
.TP
.BR TIOCLINUX ", " subcode = TIOCL_GETMOUSEREPORTING
.I argp
points to a char which is set to the value of the kernel
variable
.IR report_mouse .
(Since Linux 1.1.33.)
.TP
.BR TIOCLINUX ", " subcode = 8
Dump screen width and height, cursor position, and all the
character-attribute pairs.
(Linux 1.1.67 through Linux 1.1.91 only.
With Linux 1.1.92 or later, read from
.I /dev/vcsa*
instead.)
.TP
.BR TIOCLINUX ", " subcode = 9
Restore screen width and height, cursor position, and all the
character-attribute pairs.
(Linux 1.1.67 through Linux 1.1.91 only.
With Linux 1.1.92 or later, write to
.I /dev/vcsa*
instead.)
.TP
.BR TIOCLINUX ", " subcode = TIOCL_SETVESABLANK
Handles the Power Saving
feature of the new generation of monitors.
VESA screen blanking mode is set to
.IR argp[1] ,
which governs what
screen blanking does:
.RS
.TP
.B 0
Screen blanking is disabled.
.TP
.B 1
The current video adapter
register settings are saved, then the controller is programmed to turn off
the vertical synchronization pulses.
This puts the monitor into "standby" mode.
If your monitor has an Off_Mode timer, then
it will eventually power down by itself.
.TP
.B 2
The current settings are saved, then both the vertical and horizontal
synchronization pulses are turned off.
This puts the monitor into "off" mode.
If your monitor has no Off_Mode timer,
or if you want your monitor to power down immediately when the
blank_timer times out, then you choose this option.
.RI ( Caution:
Powering down frequently will damage the monitor.)
(Since Linux 1.1.76.)
.RE
.TP
.BR TIOCLINUX ", " subcode = TIOCL_SETKMSGREDIRECT
Change target of kernel messages ("console"):
by default, and if this is set to
.BR 0 ,
messages are written to the currently active VT.
The VT to write to is a single byte following
.BR subcode .
(Since Linux 2.5.36.)
.TP
.BR TIOCLINUX ", " subcode = TIOCL_GETFGCONSOLE
Returns the number of VT currently in foreground.
(Since Linux 2.5.36.)
.TP
.BR TIOCLINUX ", " subcode = TIOCL_SCROLLCONSOLE
Scroll the foreground VT by the specified amount of
.I lines
down,
or half the screen if
.BR 0 .
.I lines
is *(((int32_t *)&subcode) + 1).
(Since Linux 2.5.67.)
.TP
.BR TIOCLINUX ", " subcode = TIOCL_BLANKSCREEN
Blank the foreground VT, ignoring "pokes" (typing):
can only be unblanked explicitly (by switching VTs, to text mode, etc.).
(Since Linux 2.5.71.)
.TP
.BR TIOCLINUX ", " subcode = TIOCL_BLANKEDSCREEN
Returns the number of VT currently blanked,
.B 0
if none.
(Since Linux 2.5.71.)
.TP
.BR TIOCLINUX ", " subcode = 16
Never used.
.TP
.BR TIOCLINUX ", " subcode = TIOCL_GETKMSGREDIRECT
Returns target of kernel messages.
(Since Linux 2.6.17.)
.SH RETURN VALUE
On success, 0 is returned (except where indicated).
On failure, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EBADF
The file descriptor is invalid.
.TP
.B EINVAL
The file descriptor or
.I argp
is invalid.
.TP
.B ENOTTY
The file descriptor is not associated with a character special device,
or the specified operation does not apply to it.
.TP
.B EPERM
Insufficient permission.
.SH NOTES
.BR Warning :
Do not regard this man page as documentation of the Linux console ioctls.
This is provided for the curious only, as an alternative to reading the
source.
Ioctl's are undocumented Linux internals, liable to be changed
without warning.
(And indeed, this page more or less describes the
situation as of kernel version 1.1.94;
there are many minor and not-so-minor
differences with earlier versions.)
.P
Very often, ioctls are introduced for communication between the
kernel and one particular well-known program (fdisk, hdparm, setserial,
tunelp, loadkeys, selection, setfont, etc.), and their behavior will be
changed when required by this particular program.
.P
Programs using these ioctls will not be portable to other versions
of UNIX, will not work on older versions of Linux, and will not work
on future versions of Linux.
.P
Use POSIX functions.
.SH SEE ALSO
.BR dumpkeys (1),
.BR kbd_mode (1),
.BR loadkeys (1),
.BR mknod (1),
.BR setleds (1),
.BR setmetamode (1),
.BR execve (2),
.BR fcntl (2),
.BR ioctl_tty (2),
.BR ioperm (2),
.BR termios (3),
.BR console_codes (4),
.BR mt (4),
.BR sd (4),
.BR tty (4),
.BR ttyS (4),
.BR vcs (4),
.BR vcsa (4),
.BR charsets (7),
.BR mapscrn (8),
.BR resizecons (8),
.BR setfont (8)
.P
.IR /usr/include/linux/kd.h ,
.I /usr/include/linux/vt.h