path: root/man4/console_ioctl.4

.\" Copyright (c) 1995 Jim Van Zandt <jrv@vanzandt.mv.com> and aeb
.\" Sun Feb 26 11:46:23 MET 1995
.\"
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.\" modify it under the terms of the GNU General Public License as
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.\" 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)
.\" "
.TH CONSOLE_IOCTLS 4 1995-09-18 "Linux" "Linux Programmer's Manual"
.SH NAME
console ioctl \- ioctl's for console terminal and virtual consoles
.SH DESCRIPTION
The following Linux-peculiar \fBioctl()\fP requests are supported.  
Each requires a third argument, assumed here to be \fIargp\fP.
.IP \fBKDGETLED\fP
Get state of LEDs.  \fIargp\fP points to a long int.  The lower three bits
of \fI*argp\fP 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

.IP \fBKDSETLED\fP
Set the LEDs.  The LEDs are set to correspond to the lower three bits of
\fIargp\fP.  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.
.LP
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.

.IP \fBKDGKBLED\fP
Get keyboard flags CapsLock, NumLock, ScrollLock (not lights).
\fIargp\fP 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.)

.IP \fBKDSKBLED\fP
Set keyboard flags CapsLock, NumLock, ScrollLock (not lights).
\fIargp\fP 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.)

.IP \fBKDGKBTYPE\fP
Get keyboard type. This returns the value KB_101, defined as 0x02.

.IP \fBKDADDIO\fP
Add I/O port as valid. Equivalent to ioperm(arg,1,1).

.IP \fBKDDELIO\fP
Delete I/O port as valid. Equivalent to ioperm(arg,1,0).

.IP \fBKDENABIO\fP
Enable I/O to video board. Equivalent to ioperm(0x3b4, 0x3df-0x3b4+1, 1).

.IP \fBKDDISABIO\fP
Disable I/O to video board. Equivalent to ioperm(0x3b4, 0x3df-0x3b4+1, 0).

.IP \fBKDSETMODE\fP
Set text/graphics mode.  \fIargp\fP is one of these:

    KD_TEXT       0x00
    KD_GRAPHICS   0x01

.IP \fBKDGETMODE\fP
Get text/graphics mode.  \fIargp\fP points to a long which is set to one
of the above values.

.IP \fBKDMKTONE\fP
Generate tone of specified length.  
The lower 16 bits of \fIargp\fP 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, \fIargp\fP = (125<<16) + 0x637 would specify
the beep normally associated with a ctrl-G.
(Thus since 0.99pl1; broken in 2.1.49-50.)

.IP \fBKIOCSOUND\fP
Start or stop sound generation.  The lower 16 bits of
\fIargp\fP specify the period in clock cycles
(that is, \fIargp\fP = 1193180/frequency).  
\fIargp\fP = 0 turns sound off.
In either case, control returns immediately.

.IP \fBGIO_CMAP\fP
Get the current default colour map from kernel.  \fIargp\fP points to
a 48-byte array.  (Since 1.3.3.)

.IP \fBPIO_CMAP\fP
Change the default text-mode colour map.  \fIargp\fP points to a
48-byte array which contains, in order, the Red, Green, and Blue
values for the 16 available screen colours: 0 is off, and 255 is full
intensity.  The default colours 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 1.3.3.)

.IP \fBGIO_FONT\fP
Gets 256-character screen font in expanded form.  \fIargp\fP points to
an 8192 byte array.  Fails with error code \fBEINVAL\fP if the
currently loaded font is a 512-character font, or if the console is
not in text mode.

.IP \fBGIO_FONTX\fP
Gets screen font and associated information.  \fIargp\fP points to a
struct consolefontdesc (see \fBPIO_FONTX\fP).  On call, the
\fIcharcount\fP field should be set to the maximum number of
characters that would fit in the buffer pointed to by \fIchardata\fP.
On return, the \fIcharcount\fP and \fIcharheight\fP are filled with
the respective data for the currently loaded font, and the
\fIchardata\fP array contains the font data if the initial value of
\fIcharcount\fP indicated enough space was available; otherwise the
buffer is untouched and \fIerrno\fP is set to \fBENOMEM\fP.  (Since
1.3.1.)

.IP \fBPIO_FONT\fP
Sets 256-character screen font.  Load font into the EGA/VGA character
generator.  \fIargp\fP points to a 8192 byte map, with 32 bytes per
character.  Only first \fIN\fP of them are used for an 8x\fIN\fP font
(0 < \fIN\fP <= 32).  This call also invalidates the Unicode mapping.

.IP \fBPIO_FONTX\fP
Sets screen font and associated rendering information.  \fIargp\fP
points to a

.nf
struct consolefontdesc {
        u_short \fIcharcount\fP;      /* characters in font (256 or 512) */
        u_short \fIcharheight\fP;     /* scan lines per character (1-32) */
        char *\fIchardata\fP;         /* font data in expanded form */
};
.fi

If necessary, the screen will be appropriately resized, and
\fBSIGWINCH\fP sent to the appropriate processes.  This call also
invalidates the Unicode mapping.  (Since 1.3.1.)

.IP \fBPIO_FONTRESET\fP
Resets the screen font, size and Unicode mapping to the bootup
defaults.  \fIargp\fP is unused, but should be set to \fBNULL\fP to
ensure compatibility with future versions of Linux.  (Since 1.3.28.)

.IP \fBGIO_SCRNMAP\fP
Get screen mapping from kernel.  \fIargp\fP 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.

.IP \fBGIO_UNISCRNMAP\fP
Get full Unicode screen mapping from kernel.  \fIargp\fP 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 1.3.1.)

.IP \fBPIO_SCRNMAP\fP
Loads the ``user definable'' (fourth) table in the kernel which maps
bytes into console screen symbols.  \fIargp\fP points to an area of
size E_TABSZ.

.IP \fBPIO_UNISCRNMAP\fP
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 1.3.1.)

.IP \fBGIO_UNIMAP\fP
Get Unicode-to-font mapping from kernel.  \fIargp\fP points to a

.nf
struct unimapdesc {
        u_short \fIentry_ct\fP;
        struct unipair *\fIentries\fP;
};
.fi

where \fIentries\fP points to an array of

.nf
struct unipair {
        u_short \fIunicode\fP;
        u_short \fIfontpos\fP;
};
.fi

(Since 1.1.92.)

.IP \fBPIO_UNIMAP\fP
Put unicode-to-font mapping in kernel.  \fIargp\fP points to a
struct unimapdesc.  (Since 1.1.92)

.IP \fBPIO_UNIMAPCLR\fP
Clear table, possibly advise hash algorithm.  \fIargp\fP points to a

.nf 
struct unimapinit {
        u_short \fIadvised_hashsize\fP;  /* 0 if no opinion */
        u_short \fIadvised_hashstep\fP;  /* 0 if no opinion */
        u_short \fIadvised_hashlevel\fP; /* 0 if no opinion */
};
.fi

(Since 1.1.92.)

.IP \fBKDGKBMODE\fP
Gets current keyboard mode.  \fIargp\fP points to a long which is set to one
of these:

    K_RAW         0x00   
    K_XLATE       0x01   
    K_MEDIUMRAW   0x02   
    K_UNICODE     0x03

.IP \fBKDSKBMODE\fP
Sets current keyboard mode.
\fIargp\fP is a long equal to one of the above values.

.IP \fBKDGKBMETA\fP
Gets meta key handling mode.  \fIargp\fP points to a long which is
set to one of these:

    K_METABIT     0x03   set high order bit 
    K_ESCPREFIX   0x04   escape prefix

.IP \fBKDSKBMETA\fP
Sets meta key handling mode.
\fIargp\fP is a long equal to one of the above values.

.IP \fBKDGKBENT\fP
Gets one entry in key translation table (keycode to action code).  
\fIargp\fP points to a

.nf
struct kbentry {
    u_char \fIkb_table\fP;
    u_char \fIkb_index\fP;
    u_short \fIkb_value\fP;
};
.fi

with the first two members filled in: 
\fIkb_table\fP selects the key table (0 <= \fIkb_table\fP < MAX_NR_KEYMAPS),
and \fIkb_index\fP is the keycode (0 <= \fIkb_index\fP < NR_KEYS).  
\fIkb_value\fP is set to the corresponding action code,
or K_HOLE if there is no such key, 
or K_NOSUCHMAP if \fIkb_table\fP is invalid.

.IP \fBKDSKBENT\fP
Sets one entry in translation table.  \fIargp\fP points to a struct kbentry.

.IP \fBKDGKBSENT\fP
Gets one function key string.  \fIargp\fP points to a

.nf
struct kbsentry {
    u_char \fIkb_func\fP;
    u_char \fIkb_string\fP[512];
};
.fi

\fIkb_string\fP is set to the (NULL terminated) string corresponding to 
the \fIkb_func\fPth function key action code.

.IP \fBKDSKBSENT\fP
Sets one function key string entry.  \fIargp\fP points to a struct kbsentry.

.IP \fBKDGKBDIACR\fP
Read kernel accent table.  \fIargp\fP points to a

.nf
struct kbdiacrs { 
    unsigned int \fIkb_cnt\fP;
    struct kbdiacr \fIkbdiacr\fP[256];
};
.fi

where \fIkb_cnt\fP is the number of entries in the array, each of which
is a

struct kbdiacr { u_char \fIdiacr\fP, \fIbase\fP, \fIresult\fP;
};

.IP \fBKDGETKEYCODE\fP
Read kernel keycode table entry (scan code to keycode).  
\fIargp\fP points to a

.nf
struct kbkeycode { unsigned int \fIscancode\fP, \fIkeycode\fP; };
.fi

\fIkeycode\fP is set to correspond to the given \fIscancode\fP.
(89 <= \fIscancode\fP <= 255 only.  
For 1 <= \fIscancode\fP <= 88, \fIkeycode\fP==\fIscancode\fP.)
(Since 1.1.63.)

.IP \fBKDSETKEYCODE\fP
Write kernel keycode table entry.  \fIargp\fP points to struct kbkeycode.
(Since 1.1.63.)

.IP \fBKDSIGACCEPT\fP
The calling process indicates its willingness to accept the signal
\fIargp\fP when it is generated by pressing an appropriate key combination.
(1 <= \fIargp\fP <= NSIG).  
(See spawn_console() in linux/drivers/char/keyboard.c.)

.IP \fBVT_OPENQRY\fP
Returns the first available (non-opened) console.
\fIargp\fP points to an int which is set to the 
number of the vt (1 <= \fI*argp\fP <= MAX_NR_CONSOLES).

.IP \fBVT_GETMODE\fP
Get mode of active vt.  \fIargp\fP points to a

.nf
struct vt_mode {
    char \fImode\fP;     /* vt mode */
    char \fIwaitv\fP;    /* if set, hang on writes if not active */
    short \fIrelsig\fP;  /* signal to raise on release req */
    short \fIacqsig\fP;  /* signal to raise on acquisition */
    short \fIfrsig\fP;   /* unused (set to 0) */
};
.fi

\&...which is set to the mode of the active vt.  
\fImode\fP is set to one of these values: 

    VT_AUTO       auto vt switching 
    VT_PROCESS    process controls switching 
    VT_ACKACQ     acknowledge switch 

.IP \fBVT_SETMODE\fP
Set mode of active vt.  \fIargp\fP points to a struct vt_mode.

.IP \fBVT_GETSTATE\fP
Get global vt state info.  \fIargp\fP points to a 

.nf
struct vt_stat {
    ushort \fIv_active\fP;  /* active vt */
    ushort \fIv_signal\fP;  /* signal to send */
    ushort \fIv_state\fP;   /* vt bitmask */
};
.fi

For each vt in use, the corresponding bit in the \fIv_state\fP member is set.
(Kernels 1.0 through 1.1.92.)

.IP \fBVT_RELDISP\fP
Release a display.

.IP \fBVT_ACTIVATE\fP
Switch to vt \fIargp\fP (1 <= \fIargp\fP <= MAX_NR_CONSOLES).

.IP \fBVT_WAITACTIVE\fP
Wait until vt \fIargp\fP has been activated.

.IP \fBVT_DISALLOCATE\fP
Deallocate the memory associated with vt \fIargp\fP.
(Since 1.1.54.)

.IP \fBVT_RESIZE\fP
Set the kernel's idea of screensize.  \fIargp\fP points to a

.nf
struct vt_sizes {
    ushort \fIv_rows\fP;       /* # rows */
    ushort \fIv_cols\fP;       /* # columns */
    ushort \fIv_scrollsize\fP; /* no longer used */
};
.fi

Note that this does not change the videomode.
See resizecons(8).  (Since 1.1.54.) 

.IP \fBVT_RESIZEX\fP
Set the kernel's idea of various screen parameters.  \fIargp\fP
points to a

.nf
struct vt_consize {
        ushort \fIv_rows\fP;          /* number of rows */
        ushort \fIv_cols\fP;          /* number of columns */
        ushort \fIv_vlin\fP;          /* number of pixel rows on screen */
        ushort \fIv_clin\fP;          /* number of pixel rows per character */
        ushort \fIv_vcol\fP;          /* number of pixel columns on screen */
        ushort \fIv_ccol\fP;          /* number of pixel columns per character */
};
.fi

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 resizecons(8).  (Since 1.3.3.)

.PP
The action of the following ioctls depends on the first byte in the struct 
pointed to by \fIargp\fP, referred to here as the \fIsubcode\fP.
These are legal only for the superuser or the owner of the current tty.
.IP "\fBTIOCLINUX, subcode=0\fP"
Dump the screen.
Disappeared in 1.1.92.  (With kernel 1.1.92 or later, read from
/dev/vcsN or /dev/vcsaN instead.)  

.IP "\fBTIOCLINUX, subcode=1\fP"
Get task information. Disappeared in 1.1.92.

.IP "\fBTIOCLINUX, subcode=2\fP"
Set selection.
\fIargp\fP points to a

   struct {char \fIsubcode\fP;
       short \fIxs\fP, \fIys\fP, \fIxe\fP, \fIye\fP;
       short \fIsel_mode\fP;
   }

\fIxs\fP and \fIys\fP are the starting column and row.
\fIxe\fP and \fIye\fP are the ending
column and row.  (Upper left corner is row=column=1.)
\fIsel_mode\fP 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.

.IP "\fBTIOCLINUX, subcode=3\fP"
Paste selection.
The characters in the selection buffer are
written to \fIfd\fP.

.IP "\fBTIOCLINUX, subcode=4\fP"
Unblank the screen.

.IP "\fBTIOCLINUX, subcode=5\fP"
Sets contents of a 256-bit look up table defining characters in a "word",
for word-by-word selection.  (Since 1.1.32.)

.IP "\fBTIOCLINUX, subcode=6\fP"
\fIargp\fP points to a char which is set to the value of the kernel
variable \fIshift_state\fP.  (Since 1.1.32.)

.IP "\fBTIOCLINUX, subcode=7\fP"
\fIargp\fP points to a char which is set to the value of the kernel
variable \fIreport_mouse\fP.  (Since 1.1.33.)

.IP "\fBTIOCLINUX, subcode=8\fP"
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.)

.IP "\fBTIOCLINUX, subcode=9\fP"
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.)  

.IP "\fBTIOCLINUX, subcode=10\fP"
Handles the Power Saving
feature of the new generation of monitors.  
VESA screen blanking mode is set to \fIargp\fP[1], which governs what
screen blanking does:

    \fI0\fP: Screen blanking is disabled.

    \fI1\fP: 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.

    \fI2\fP: 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.  
(\fICaution:\fP Powering down frequently will damage the monitor.)  

(Since 1.1.76.)

.SH "RETURN VALUE"
On success, 0 is returned. On error \-1 is returned, and \fIerrno\fP is set.
.SH ERRORS
\fIerrno\fP may take on these values:

.TP
.B EBADF
The file descriptor is invalid.
.TP
.B
ENOTTY
The file descriptor is not associated with a character special device,
or the specified request does not apply to it.
.TP
.B EINVAL
The file descriptor or \fIargp\fP is invalid.
.TP
.B EPERM
Insufficient permission.
.SH 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, hdparm, setserial,
tunelp, loadkeys, selection, setfont, etc.), and their behavior will be
changed when required by this particular program.

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.

.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 ioperm (2),
.BR termios (3),
.BR console (4),
.BR console_codes (4),
.BR mt (4),
.BR sd (4),
.BR tty (4),
.BR tty_ioctl (4),
.BR ttys (4),
.BR vcs (4),
.BR vcsa (4),
.BR charsets (7),
.BR mapscrn (8),
.BR resizecons (8),
.BR setfont (8),
.IR /usr/include/linux/kd.h ,
.I /usr/include/linux/vt.h