NAME | DESCRIPTION | RETURN VALUE | ERRORS | NOTES | SEE ALSO | COLOPHON

CONSOLE_IOCTL(4)          Linux Programmer's Manual         CONSOLE_IOCTL(4)

NAME         top

       console_ioctl - ioctls for console terminal and virtual consoles

DESCRIPTION         top

       The following Linux-specific ioctl(2) requests are supported.  Each
       requires a third argument, assumed here to be argp.

       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 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 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 one of these:

              KD_TEXT       0x00
              KD_GRAPHICS   0x01

       KDGETMODE
              Get text/graphics mode.  argp points to an int 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.  (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 a 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
              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 {
                      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.)

       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) */
                  };

              which is set to the mode of the active vt.  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 {
                      unsigned short v_active;  /* active vt */
                      unsigned short v_signal;  /* signal to send */
                      unsigned short v_state;   /* vt bit mask */
                  };

              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 Linux
              1.1.54.)

       VT_RESIZE
              Set the kernel's idea of screensize.  argp points to a

                  struct vt_sizes {
                      unsigned short v_rows;       /* # rows */
                      unsigned short v_cols;       /* # columns */
                      unsigned short v_scrollsize; /* no longer used */
                  };

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

       VT_RESIZEX
              Set the kernel's idea of various screen parameters.  argp
              points to a

                  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 */
                  };

              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 Linux 1.3.3.)

       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
       terminal.

       TIOCLINUX, subcode=0
              Dump the screen.  Disappeared in Linux 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 Linux 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 Linux
              1.1.32.)

       TIOCLINUX, subcode=6
              argp points to a char which is set to the value of the kernel
              variable shift_state.  (Since Linux 1.1.32.)

       TIOCLINUX, subcode=7
              argp points to a char which is set to the value of the kernel
              variable report_mouse.  (Since Linux 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[1], which
              governs what screen blanking does:

              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 Linux 1.1.76.)

RETURN VALUE         top

       On success, 0 is returned.  On error, -1 is returned, and errno is
       set.

ERRORS         top

       errno may take on these values:

       EBADF  The file descriptor is invalid.

       ENOTTY The file descriptor is not associated with a character special
              device, or the specified request does not apply to it.

       EINVAL The file descriptor or argp is invalid.

       EPERM  Insufficient permission.

NOTES         top

       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.)

       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.

       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.

       Use POSIX functions.

SEE ALSO         top

       dumpkeys(1), kbd_mode(1), loadkeys(1), mknod(1), setleds(1),
       setmetamode(1), execve(2), fcntl(2), ioperm(2), termios(3),
       console_codes(4), mt(4), sd(4), tty(4), tty_ioctl(4), ttyS(4),
       vcs(4), vcsa(4), charsets(7), mapscrn(8), resizecons(8), setfont(8)

       /usr/include/linux/kd.h, /usr/include/linux/vt.h

COLOPHON         top

       This page is part of release 4.07 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                            2016-07-17                 CONSOLE_IOCTL(4)