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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | SEE ALSO | COLOPHON |
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ioctl_kd(2) System Calls Manual ioctl_kd(2)
ioctl_kd - ioctls for console terminal and virtual consoles
#include <linux/kd.h> /* Definition of op constants */
#include <sys/ioctl.h>
int ioctl(int fd, unsigned long op, void *argp);
The following Linux-specific ioctl(2) operations are supported for
console terminals and virtual consoles.
KDGETLED
Get state of LEDs. argp points to a char. The lower three
bits of *argp are set to the state of the LEDs, as follows:
LED_CAP 0x04 caps lock led
LED_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 the unsigned long integer in 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.
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.
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 Linux 1.1.54.)
KDSKBLED
Set keyboard flags CapsLock, NumLock, ScrollLock (not
lights). 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.)
KDGKBTYPE
Get keyboard type. This returns the value KB_101, defined
as 0x02.
KDADDIO
Add I/O port as valid. Equivalent to ioperm(arg,1,1).
KDDELIO
Delete I/O port as valid. Equivalent to ioperm(arg,1,0).
KDENABIO
Enable I/O to video board. Equivalent to ioperm(0x3b4,
0x3df-0x3b4+1, 1).
KDDISABIO
Disable I/O to video board. Equivalent to ioperm(0x3b4,
0x3df-0x3b4+1, 0).
KDSETMODE
Set text/graphics mode. argp is an unsigned integer
containing one of:
KD_TEXT 0x00
KD_GRAPHICS 0x01
KDGETMODE
Get text/graphics mode. argp points to an int which is set
to one of the values shown above for KDSETMODE.
KDMKTONE
Generate tone of specified length. The lower 16 bits of
the unsigned long integer in 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. (Thus since Linux 0.99pl1; broken in Linux
2.1.49-50.)
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 immediately.
GIO_CMAP
Get the current default color map from kernel. argp points
to a 48-byte array. (Since Linux 1.3.3.)
PIO_CMAP
Change the default text-mode color map. 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.)
GIO_FONT
Gets 256-character screen font in expanded form. argp
points to an 8192-byte array. Fails with error code EINVAL
if the currently loaded font is a 512-character font, or if
the console is not in text mode.
GIO_FONTX
Gets screen font and associated information. argp points
to a struct consolefontdesc (see PIO_FONTX). On call, the
charcount field should be set to the maximum number of
characters that would fit in the buffer pointed to by
chardata. On return, the charcount and charheight are
filled with the respective data for the currently loaded
font, and the chardata array contains the font data if the
initial value of charcount indicated enough space was
available; otherwise the buffer is untouched and errno is
set to ENOMEM. (Since Linux 1.3.1.)
PIO_FONT
Sets 256-character screen font. Load font into the EGA/VGA
character generator. argp points to an 8192-byte map, with
32 bytes per character. Only the first N of them are used
for an 8xN font (0 < N <= 32). This call also invalidates
the Unicode mapping.
PIO_FONTX
Sets screen font and associated rendering information.
argp points to a
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 */
};
If necessary, the screen will be appropriately resized, and
SIGWINCH sent to the appropriate processes. This call also
invalidates the Unicode mapping. (Since Linux 1.3.1.)
PIO_FONTRESET
Resets the screen font, size, and Unicode mapping to the
bootup defaults. argp is unused, but should be set to NULL
to ensure compatibility with future versions of Linux.
(Since Linux 1.3.28.)
GIO_SCRNMAP
Get screen mapping from kernel. 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.
GIO_UNISCRNMAP
Get full Unicode screen mapping from kernel. argp points
to an area of size 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.)
PIO_SCRNMAP
Loads the "user definable" (fourth) table in the kernel
which maps bytes into console screen symbols. argp points
to an area of size E_TABSZ.
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.)
GIO_UNIMAP
Get Unicode-to-font mapping from kernel. argp points to a
struct unimapdesc {
unsigned short entry_ct;
struct unipair *entries;
};
where entries points to an array of
struct unipair {
unsigned short unicode;
unsigned short fontpos;
};
(Since Linux 1.1.92.)
PIO_UNIMAP
Put unicode-to-font mapping in kernel. argp points to a
struct unimapdesc. (Since Linux 1.1.92)
PIO_UNIMAPCLR
Clear table, possibly advise hash algorithm. argp points
to a
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 */
};
(Since Linux 1.1.92.)
KDGKBMODE
Gets current keyboard mode. argp points to a long which is
set to one of these:
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 */
KDSKBMODE
Sets current keyboard mode. argp is a long equal to one of
the values shown for KDGKBMODE.
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 values shown above for KDGKBMETA.
KDGKBENT
Gets one entry in key translation table (keycode to action
code). argp points to a
struct kbentry {
unsigned char kb_table;
unsigned char kb_index;
unsigned 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 corresponding 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 {
unsigned char kb_func;
unsigned 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 {
unsigned char diacr;
unsigned char base;
unsigned char result;
};
KDGETKEYCODE
Read kernel keycode table entry (scan code to keycode).
argp points to a
struct kbkeycode {
unsigned int scancode;
unsigned int keycode;
};
keycode is set to correspond to the given scancode. (89 <=
scancode <= 255 only. For 1 <= scancode <= 88,
keycode==scancode.) (Since Linux 1.1.63.)
KDSETKEYCODE
Write kernel keycode table entry. argp points to a struct
kbkeycode. (Since Linux 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.)
On success, 0 is returned (except where indicated). On failure,
-1 is returned, and errno is set to indicate the error.
EINVAL argp is invalid.
Linux.
ioctl(2), ioctl_console(2)
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user-space interface documentation) project. Information about
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Linux man-pages 6.15 2025-05-17 ioctl_kd(2)
Pages that refer to this page: ioctl_console(2)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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