CONSOLE_IOCTLS

NAME
DESCRIPTION
RETURN VALUES
ERRORS
WARNING
SEE ALSO

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 supported. 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: displaying 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 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 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 immediately.

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 character 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 symbols. 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 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 {
    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 keycode). 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 corner is row=column=1.) 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 the static array sel_buffer in devices/char/console.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 generation 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 monitor 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), loadkeys(1), gpm(8), consolechars(8), etc.), and their behavior will be changed when required by these particular programs.

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), resizecons(8), /usr/include/linux/kd.h, /usr/include/linux/vt.h.