Computer Science
CONSOLE_IOCTLS(4) Linux Programmer's Manual CONSOLE_IOCTLS(4)
NAME
console ioctl's- ioctl's for console terminal and virtual
consoles
DESCRIPTION
WARNING: If you use the following information you are
going to burn yourself.
WARNING: ioctl's are undocumented Linux internals, liable
to be changed without warning. Use POSIX functions where
available.
The following Linux-peculiar ioctl() requests are sup-
ported. Each requires a third argument, assumed here to
be argp.
KDGETLED
Get state of LEDs. argp points to a long int. The
lower three bits of *argp are set to the state of
the LEDs, as follows:
LED_CAP 0x04 caps lock led
LEC_NUM 0x02 num lock led
LED_SCR 0x01 scroll lock led
KDSETLED
Set the LEDs. The LEDs are set to correspond to
the lower three bits of argp. However, if a higher
order bit is set, the LEDs revert to normal: dis-
playing the state of the keyboard functions of caps
lock, num lock, and scroll lock.
Before 1.1.54, the leds just reflected the state of
the corresponding keyboard flags, and
KDGETLED/KDSETLED would also change the keyboard
flags. Since 1.1.54 the leds can be made to display
arbitrary information, but by default they display
the keyboard flags. The following two ioctl's are
used to access the keyboard flags.
KDGKBLED
Get keyboard flags CapsLock, NumLock, ScrollLock
(not lights). 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 1.1.54.)
KDSKBLED
Set keyboard flags CapsLock, NumLock, ScrollLock
(not lights). argp 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
1.1.54.)
KDGKBTYPE
Get keyboard type. This returns the value KB_101,
defined as 0x02.
KDADDIO
Add I/O port as valid. Equivalent to iop-
erm(arg,1,1).
KDDELIO
Delete I/O port as valid. Equivalent to iop-
erm(arg,1,0).
KDENABIO
Enable I/O to video board. Equivalent to iop-
erm(0x3b4, 0x3df-0x3b4+1, 1).
KDDISABIO
Disable I/O to video board. Equivalent to iop-
erm(0x3b4, 0x3df-0x3b4+1, 0).
KDSETMODE
Set text/graphics mode. argp is one of these:
KD_TEXT 0x00
KD_GRAPHICS 0x01
KDGETMODE
Get text/graphics mode. argp points to a long
which is set to one of the above values.
KDMKTONE
Generate tone of specified length. The lower 16
bits of 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, argp =
(125<<16) + 0x637 would specify the beep normally
associated with a ctrl-G.
KIOCSOUND
Start or stop sound generation. The lower 16 bits
of argp specify the period in clock cycles (that
is, argp = 1193180/frequency). argp = 0 turns
sound off. In either case, control returns immedi-
ately.
GIO_FONT
Gets screen font in expanded form. argp points to
an 8192 byte array.
PIO_FONT
Sets screen font. Load font into the EGA/VGA char-
acter generator. argp points to a 8192 byte map,
with 32 bytes per character. Only first N of them
are used for an 8xN font (0 < N <= 32).
GIO_SCRNMAP
Get screen mapping from kernel. argp points to an
area of size E_TABSZ.
PIO_SCRNMAP
Loads the "user definable" (fourth) table in the
kernel which maps bytes into console screen sym-
bols. argp points to an area of size E_TABSZ.
GIO_UNIMAP
Get unicode-to-font mapping from kernel. argp
points to a
struct unimapdesc {
u_short entry_ct;
struct unipair *entries;
};
where entries points to an array of
struct unipair {
u_short unicode;
u_short fontpos;
};
(Since 1.1.92.)
PIO_UNIMAP
Put unicode-to-font mapping in kernel. argp points
to a struct unimapdesc. (Since 1.1.92)
PIO_UNIMAPCLR
Clear table, possibly advise hash algorithm. argp
points to a
struct unimapinit {
u_short advised_hashsize; /* 0 if no opinion */
u_short advised_hashstep; /* 0 if no opinion */
u_short advised_hashlevel; /* 0 if no opinion */
};
(Since 1.1.92.)
KDGKBMODE
Gets current keyboard mode. argp points to a long
which is set to one of these:
K_RAW 0x00
K_XLATE 0x01
K_MEDIUMRAW 0x02
K_UNICODE 0x03
KDSKBMODE
Sets current keyboard mode. argp is a long equal
to one of the above values.
KDGKBMETA
Gets meta key handling mode. argp points to a long
which is set to one of these:
K_METABIT 0x03 set high order bit
K_ESCPREFIX 0x04 escape prefix
KDSKBMETA
Sets meta key handling mode. argp is a long equal
to one of the above values.
KDGKBENT
Gets one entry in key translation table (keycode to
action code). argp points to a
struct kbentry {
u_char kb_table;
u_char kb_index;
u_short kb_value;
};
with the first two members filled in: kb_table
selects the key table (0 <= kb_table <
MAX_NR_KEYMAPS), and kb_index is the keycode (0 <=
kb_index < NR_KEYS). kb_value is set to the corre-
sponding action code, or K_HOLE if there is no such
key, or K_NOSUCHMAP if kb_table is invalid.
KDSKBENT
Sets one entry in translation table. argp points
to a struct kbentry.
KDGKBSENT
Gets one function key string. argp points to a
struct kbsentry {
u_char kb_func;
u_char kb_string[512];
};
kb_string is set to the (NULL terminated) string
corresponding to the kb_functh function key action
code.
KDSKBSENT
Sets one function key string entry. argp points to
a struct kbsentry.
KDGKBDIACR
Read kernel accent table. argp points to a
struct kbdiacrs {
unsigned int kb_cnt;
struct kbdiacr kbdiacr[256];
};
where kb_cnt is the number of entries in the array,
each of which is a
struct kbdiacr { u_char diacr, base, result; };
KDGETKEYCODE
Read kernel keycode table entry (scan code to key-
code). argp points to a
struct kbkeycode { unsigned int scancode, keycode; };
keycode is set to correspond to the given scancode.
(89 <= scancode <= 255 only. For 1 <= scancode <=
88, keycode==scancode.) (Since 1.1.63.)
KDSETKEYCODE
Write kernel keycode table entry. argp points to
struct kbkeycode. (Since 1.1.63.)
KDSIGACCEPT
The calling process indicates its willingness to
accept the signal argp when it is generated by
pressing an appropriate key combination. (1 <=
argp <= NSIG). (See spawn_console() in
linux/drivers/char/keyboard.c.)
VT_OPENQRY
Returns the first available (non-opened) console.
argp points to an int which is set to the number of
the vt (1 <= *argp <= MAX_NR_CONSOLES).
VT_GETMODE
Get mode of active vt. argp points to a
struct vt_mode {
char mode; /* vt mode */
char waitv; /* if set, hang on writes if not active */
short relsig; /* signal to raise on release req */
short acqsig; /* signal to raise on acquisition */
short frsig; /* unused (set to 0) */
};
mode is set to one of these values:
VT_AUTO auto vt switching
VT_PROCESS process controls switching
VT_ACKACQ acknowledge switch
VT_SETMODE
Set mode of active vt. argp points to a struct
vt_mode.
VT_GETSTATE
Get global vt state info. argp points to a
struct vt_stat {
ushort v_active; /* active vt */
ushort v_signal; /* signal to send */
ushort v_state; /* vt bitmask */
};
For each vt in use, the corresponding bit in the
v_state member is set. (Kernels 1.0 through
1.1.92.)
VT_RELDISP
Release a display.
VT_ACTIVATE
Switch to vt argp (1 <= argp <= MAX_NR_CONSOLES).
VT_WAITACTIVE
Wait until vt argp has been activated.
VT_DISALLOCATE
Deallocate the memory associated with vt argp.
(Since 1.1.54.)
VT_RESIZE
Set kernel's idea of screensize. argp points to a
struct vt_sizes {
ushort v_rows; /* # rows */
ushort v_cols; /* # columns */
ushort v_scrollsize; /* no longer used */
};
(Since 1.1.54.) Note that this does not change the
videomode. See resizecons(8).
The action of the following ioctls depends on the first
byte in the struct pointed to by argp, referred to here as
the subcode. These are legal only for the superuser or
the owner of the current tty.
TIOCLINUX, subcode=0
Dump the screen. Disappeared in 1.1.92. (With
kernel 1.1.92 or later, read from /dev/vcsN or
/dev/vcsaN instead.)
TIOCLINUX, subcode=1
Get task information. Disappeared in 1.1.92.
TIOCLINUX, subcode=2
Set selection. argp points to a
struct {char subcode;
short xs, ys, xe, ye;
short sel_mode;
}
xs and ys are the starting column and row. xe and
ye are the ending column and row. (Upper left cor-
ner is row=column=1.) sel_mode is 0 for character-
by-character selection, 1 for word-by-word selec-
tion, or 2 for line-by-line selection. The indi-
cated screen characters are highlighted and saved
in the static array sel_buffer in devices/char/con-
sole.c.
TIOCLINUX, subcode=3
Paste selection. The characters in the selection
buffer are written to fd.
TIOCLINUX, subcode=4
Unblank the screen.
TIOCLINUX, subcode=5
Sets contents of a 256-bit look up table defining
characters in a "word", for word-by-word selection.
(Since 1.1.32.)
TIOCLINUX, subcode=6
argp points to a char which is set to the value of
the kernel variable shift_state. (Since 1.1.32.)
TIOCLINUX, subcode=7
argp points to a char which is set to the value of
the kernel variable report_mouse. (Since 1.1.33.)
TIOCLINUX, subcode=8
Dump screen width and height, cursor position, and
all the character-attribute pairs. (Kernels 1.1.67
through 1.1.91 only. With kernel 1.1.92 or later,
read from /dev/vcsa* instead.)
TIOCLINUX, subcode=9
Restore screen width and height, cursor position,
and all the character-attribute pairs. (Kernels
1.1.67 through 1.1.91 only. With kernel 1.1.92 or
later, write to /dev/vcsa* instead.)
TIOCLINUX, subcode=10
Handles the Power Saving feature of the new genera-
tion of monitors. VESA screen blanking mode is set
to argp, which is one of:
0: Screen blanking is disabled.
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 mon-
itor has an Off_Mode timer, then it will eventually
power down by itself.
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. (Caution: Powering down frequently
will damage the monitor.)
(Since 1.1.76.)
RETURN VALUES
-1 for error, and errno is set.
ERRORS
errno may take on these values:
EBADF file descriptor is invalid.
ENOTTY file descriptor is not associated with a character
special device, or the specified request does not
apply to it.
EINVAL file descriptor or argp is invalid.
EPERM permission violation.
WARNING
Do not regard this man page as documentation of the Linux
console ioctl's. 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.)
Very often, ioctl's are introduced for communication
between the kernel and one particular well-known program
(fdisk(8), hdparm(8), setserial(8), tunelp(8), load-
keys(1), gpm(8), consolechars(8), etc.), and their behav-
ior will be changed when required by these particular pro-
grams.
Programs using these ioctl's 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.
Use POSIX functions.
SEE ALSO
kbd_mode(1), loadkeys(1), dumpkeys(1), mknod(1),
setleds(1), setmetamode(1), ioperm(2), termios(2),
execve(2), fcntl(2), mt(4), sd(4), tty(4), ttys(4),
vcs(4), vcsa(4), mapscrn(8), consolechars(8), resize-
cons(8), /usr/include/linux/kd.h, /usr/include/linux/vt.h.
Linux 28 Oct 1997 1
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