ioctl_console(2) — Linux manual page

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IOCTL_CONSOLE(2)        Linux Programmer's Manual       IOCTL_CONSOLE(2)

NAME         top

       ioctl_console - ioctls for console terminal and virtual consoles

DESCRIPTION         top

       The following Linux-specific ioctl(2) requests are supported for
       console terminals and virtual consoles.  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 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.)

       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 failure, -1 is returned, and errno
       is set to indicate the error.

ERRORS         top

       EBADF  The file descriptor is invalid.

       EINVAL The file descriptor or argp is invalid.

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

       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), ioctl_tty(2), ioperm(2),
       termios(3), console_codes(4), mt(4), sd(4), tty(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 5.13 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                          2021-03-22               IOCTL_CONSOLE(2)

Pages that refer to this page: ioctl(2)ioctl_tty(2)termios(3)console_codes(4)tty(4)vcs(4)