1Ioctl Numbers
   219 October 1999
   3Michael Elizabeth Chastain
   6If you are adding new ioctl's to the kernel, you should use the _IO
   7macros defined in <linux/ioctl.h>:
   9    _IO    an ioctl with no parameters
  10    _IOW   an ioctl with write parameters (copy_from_user)
  11    _IOR   an ioctl with read parameters  (copy_to_user)
  12    _IOWR  an ioctl with both write and read parameters.
  14'Write' and 'read' are from the user's point of view, just like the
  15system calls 'write' and 'read'.  For example, a SET_FOO ioctl would
  16be _IOW, although the kernel would actually read data from user space;
  17a GET_FOO ioctl would be _IOR, although the kernel would actually write
  18data to user space.
  20The first argument to _IO, _IOW, _IOR, or _IOWR is an identifying letter
  21or number from the table below.  Because of the large number of drivers,
  22many drivers share a partial letter with other drivers.
  24If you are writing a driver for a new device and need a letter, pick an
  25unused block with enough room for expansion: 32 to 256 ioctl commands.
  26You can register the block by patching this file and submitting the
  27patch to Linus Torvalds.  Or you can e-mail me at <> and
  28I'll register one for you.
  30The second argument to _IO, _IOW, _IOR, or _IOWR is a sequence number
  31to distinguish ioctls from each other.  The third argument to _IOW,
  32_IOR, or _IOWR is the type of the data going into the kernel or coming
  33out of the kernel (e.g.  'int' or 'struct foo').  NOTE!  Do NOT use
  34sizeof(arg) as the third argument as this results in your ioctl thinking
  35it passes an argument of type size_t.
  37Some devices use their major number as the identifier; this is OK, as
  38long as it is unique.  Some devices are irregular and don't follow any
  39convention at all.
  41Following this convention is good because:
  43(1) Keeping the ioctl's globally unique helps error checking:
  44    if a program calls an ioctl on the wrong device, it will get an
  45    error rather than some unexpected behaviour.
  47(2) The 'strace' build procedure automatically finds ioctl numbers
  48    defined with _IO, _IOW, _IOR, or _IOWR.
  50(3) 'strace' can decode numbers back into useful names when the
  51    numbers are unique.
  53(4) People looking for ioctls can grep for them more easily when
  54    this convention is used to define the ioctl numbers.
  56(5) When following the convention, the driver code can use generic
  57    code to copy the parameters between user and kernel space.
  59This table lists ioctls visible from user land for Linux/x86.  It contains
  60most drivers up to 2.6.31, but I know I am missing some.  There has been
  61no attempt to list non-X86 architectures or ioctls from drivers/staging/.
  63Code  Seq#(hex) Include File            Comments
  650x00    00-1F   linux/fs.h              conflict!
  660x00    00-1F   scsi/scsi_ioctl.h       conflict!
  670x00    00-1F   linux/fb.h              conflict!
  680x00    00-1F   linux/wavefront.h       conflict!
  690x02    all     linux/fd.h
  700x03    all     linux/hdreg.h
  710x04    D2-DC   linux/umsdos_fs.h       Dead since 2.6.11, but don't reuse these.
  720x06    all     linux/lp.h
  730x09    all     linux/raid/md_u.h
  740x10    00-0F   drivers/char/s390/vmcp.h
  750x12    all     linux/fs.h
  76                linux/blkpg.h
  770x1b    all     InfiniBand Subsystem    <>
  780x20    all     drivers/cdrom/cm206.h
  790x22    all     scsi/sg.h
  80'#'     00-3F   IEEE 1394 Subsystem     Block for the entire subsystem
  81'$'     00-0F   linux/perf_counter.h, linux/perf_event.h
  82'&'     00-07   drivers/firewire/nosy-user.h
  83'1'     00-1F   <linux/timepps.h>       PPS kit from Ulrich Windl
  84                                        <>
  85'2'     01-04   linux/i2o.h
  86'3'     00-0F   drivers/s390/char/raw3270.h     conflict!
  87'3'     00-1F   linux/suspend_ioctls.h  conflict!
  88                and kernel/power/user.c
  89'8'     all                             SNP8023 advanced NIC card
  90                                        <>
  91';'     64-7F   linux/vfio.h
  92'@'     00-0F   linux/radeonfb.h        conflict!
  93'@'     00-0F   drivers/video/aty/aty128fb.c    conflict!
  94'A'     00-1F   linux/apm_bios.h        conflict!
  95'A'     00-0F   linux/agpgart.h         conflict!
  96                and drivers/char/agp/compat_ioctl.h
  97'A'     00-7F   sound/asound.h          conflict!
  98'B'     00-1F   linux/cciss_ioctl.h     conflict!
  99'B'     00-0F   include/linux/pmu.h     conflict!
 100'B'     C0-FF                           advanced bbus
 101                                        <>
 102'C'     all     linux/soundcard.h       conflict!
 103'C'     01-2F   linux/capi.h            conflict!
 104'C'     F0-FF   drivers/net/wan/cosa.h  conflict!
 105'D'     all     arch/s390/include/asm/dasd.h
 106'D'     40-5F   drivers/scsi/dpt/dtpi_ioctl.h
 107'D'     05      drivers/scsi/pmcraid.h
 108'E'     all     linux/input.h           conflict!
 109'E'     00-0F   xen/evtchn.h            conflict!
 110'F'     all     linux/fb.h              conflict!
 111'F'     01-02   drivers/scsi/pmcraid.h  conflict!
 112'F'     20      drivers/video/fsl-diu-fb.h      conflict!
 113'F'     20      drivers/video/intelfb/intelfb.h conflict!
 114'F'     20      linux/ivtvfb.h          conflict!
 115'F'     20      linux/matroxfb.h        conflict!
 116'F'     20      drivers/video/aty/atyfb_base.c  conflict!
 117'F'     00-0F   video/da8xx-fb.h        conflict!
 118'F'     80-8F   linux/arcfb.h           conflict!
 119'F'     DD      video/sstfb.h           conflict!
 120'G'     00-3F   drivers/misc/sgi-gru/grulib.h   conflict!
 121'G'     00-0F   linux/gigaset_dev.h     conflict!
 122'H'     00-7F   linux/hiddev.h          conflict!
 123'H'     00-0F   linux/hidraw.h          conflict!
 124'H'     01      linux/mei.h             conflict!
 125'H'     00-0F   sound/asound.h          conflict!
 126'H'     20-40   sound/asound_fm.h       conflict!
 127'H'     80-8F   sound/sfnt_info.h       conflict!
 128'H'     10-8F   sound/emu10k1.h         conflict!
 129'H'     10-1F   sound/sb16_csp.h        conflict!
 130'H'     10-1F   sound/hda_hwdep.h       conflict!
 131'H'     40-4F   sound/hdspm.h           conflict!
 132'H'     40-4F   sound/hdsp.h            conflict!
 133'H'     90      sound/usb/usx2y/usb_stream.h
 134'H'     C0-F0   net/bluetooth/hci.h     conflict!
 135'H'     C0-DF   net/bluetooth/hidp/hidp.h       conflict!
 136'H'     C0-DF   net/bluetooth/cmtp/cmtp.h       conflict!
 137'H'     C0-DF   net/bluetooth/bnep/bnep.h       conflict!
 138'H'     F1      linux/hid-roccat.h      <>
 139'I'     all     linux/isdn.h            conflict!
 140'I'     00-0F   drivers/isdn/divert/isdn_divert.h       conflict!
 141'I'     40-4F   linux/mISDNif.h         conflict!
 142'J'     00-1F   drivers/scsi/gdth_ioctl.h
 143'K'     all     linux/kd.h
 144'L'     00-1F   linux/loop.h            conflict!
 145'L'     10-1F   drivers/scsi/mpt2sas/mpt2sas_ctl.h      conflict!
 146'L'     E0-FF   linux/ppdd.h            encrypted disk device driver
 147                                        <>
 148'M'     all     linux/soundcard.h       conflict!
 149'M'     01-16   mtd/mtd-abi.h           conflict!
 150                and drivers/mtd/mtdchar.c
 151'M'     01-03   drivers/scsi/megaraid/megaraid_sas.h
 152'M'     00-0F   drivers/video/fsl-diu-fb.h      conflict!
 153'N'     00-1F   drivers/usb/scanner.h
 154'N'     40-7F   drivers/block/nvme.c
 155'O'     00-06   mtd/ubi-user.h          UBI
 156'P'     all     linux/soundcard.h       conflict!
 157'P'     60-6F   sound/sscape_ioctl.h    conflict!
 158'P'     00-0F   drivers/usb/class/usblp.c       conflict!
 159'Q'     all     linux/soundcard.h
 160'R'     00-1F   linux/random.h          conflict!
 161'R'     01      linux/rfkill.h          conflict!
 162'R'     C0-DF   net/bluetooth/rfcomm.h
 163'S'     all     linux/cdrom.h           conflict!
 164'S'     80-81   scsi/scsi_ioctl.h       conflict!
 165'S'     82-FF   scsi/scsi.h             conflict!
 166'S'     00-7F   sound/asequencer.h      conflict!
 167'T'     all     linux/soundcard.h       conflict!
 168'T'     00-AF   sound/asound.h          conflict!
 169'T'     all     arch/x86/include/asm/ioctls.h   conflict!
 170'T'     C0-DF   linux/if_tun.h          conflict!
 171'U'     all     sound/asound.h          conflict!
 172'U'     00-CF   linux/uinput.h          conflict!
 173'U'     00-EF   linux/usbdevice_fs.h
 174'U'     C0-CF   drivers/bluetooth/hci_uart.h
 175'V'     all     linux/vt.h              conflict!
 176'V'     all     linux/videodev2.h       conflict!
 177'V'     C0      linux/ivtvfb.h          conflict!
 178'V'     C0      linux/ivtv.h            conflict!
 179'V'     C0      media/davinci/vpfe_capture.h    conflict!
 180'V'     C0      media/si4713.h          conflict!
 181'V'     C0-CF   drivers/media/video/mxb.h       conflict!
 182'W'     00-1F   linux/watchdog.h        conflict!
 183'W'     00-1F   linux/wanrouter.h       conflict!
 184'W'     00-3F   sound/asound.h          conflict!
 185'X'     all     fs/xfs/xfs_fs.h         conflict!
 186                and fs/xfs/linux-2.6/xfs_ioctl32.h
 187                and include/linux/falloc.h
 188                and linux/fs.h
 189'X'     all     fs/ocfs2/ocfs_fs.h      conflict!
 190'X'     01      linux/pktcdvd.h         conflict!
 191'Y'     all     linux/cyclades.h
 192'Z'     14-15   drivers/message/fusion/mptctl.h
 193'['     00-07   linux/usb/tmc.h         USB Test and Measurement Devices
 194                                        <>
 195'a'     all     linux/atm*.h, linux/sonet.h     ATM on linux
 196                                        <>
 197'b'     00-FF                           conflict! bit3 vme host bridge
 198                                        <>
 199'c'     all     linux/cm4000_cs.h       conflict!
 200'c'     00-7F   linux/comstats.h        conflict!
 201'c'     00-7F   linux/coda.h            conflict!
 202'c'     00-1F   linux/chio.h            conflict!
 203'c'     80-9F   arch/s390/include/asm/chsc.h    conflict!
 204'c'     A0-AF   arch/x86/include/asm/msr.h      conflict!
 205'd'     00-FF   linux/char/drm/drm/h    conflict!
 206'd'     02-40   pcmcia/ds.h             conflict!
 207'd'     10-3F   drivers/media/video/dabusb.h    conflict!
 208'd'     C0-CF   drivers/media/video/saa7191.h   conflict!
 209'd'     F0-FF   linux/digi1.h
 210'e'     all     linux/digi1.h           conflict!
 211'e'     00-1F   drivers/net/irda/irtty-sir.h    conflict!
 212'f'     00-1F   linux/ext2_fs.h         conflict!
 213'f'     00-1F   linux/ext3_fs.h         conflict!
 214'f'     00-0F   fs/jfs/jfs_dinode.h     conflict!
 215'f'     00-0F   fs/ext4/ext4.h          conflict!
 216'f'     00-0F   linux/fs.h              conflict!
 217'f'     00-0F   fs/ocfs2/ocfs2_fs.h     conflict!
 218'g'     00-0F   linux/usb/gadgetfs.h
 219'g'     20-2F   linux/usb/g_printer.h
 220'h'     00-7F                           conflict! Charon filesystem
 221                                        <>
 222'h'     00-1F   linux/hpet.h            conflict!
 223'h'     80-8F   fs/hfsplus/ioctl.c
 224'i'     00-3F   linux/i2o-dev.h         conflict!
 225'i'     0B-1F   linux/ipmi.h            conflict!
 226'i'     80-8F   linux/i8k.h
 227'j'     00-3F   linux/joystick.h
 228'k'     00-0F   linux/spi/spidev.h      conflict!
 229'k'     00-05   video/kyro.h            conflict!
 230'k'     10-17   linux/hsi/hsi_char.h    HSI character device
 231'l'     00-3F   linux/tcfs_fs.h         transparent cryptographic file system
 232                                        <*/>
 233'l'     40-7F   linux/udf_fs_i.h        in development:
 234                                        <>
 235'm'     00-09   linux/mmtimer.h         conflict!
 236'm'     all     linux/mtio.h            conflict!
 237'm'     all     linux/soundcard.h       conflict!
 238'm'     all     linux/synclink.h        conflict!
 239'm'     00-19   drivers/message/fusion/mptctl.h conflict!
 240'm'     00      drivers/scsi/megaraid/megaraid_ioctl.h  conflict!
 241'm'     00-1F   net/irda/irmod.h        conflict!
 242'n'     00-7F   linux/ncp_fs.h and fs/ncpfs/ioctl.c
 243'n'     80-8F   linux/nilfs2_fs.h       NILFS2
 244'n'     E0-FF   linux/matroxfb.h        matroxfb
 245'o'     00-1F   fs/ocfs2/ocfs2_fs.h     OCFS2
 246'o'     00-03   mtd/ubi-user.h          conflict! (OCFS2 and UBI overlaps)
 247'o'     40-41   mtd/ubi-user.h          UBI
 248'o'     01-A1   linux/dvb/*.h           DVB
 249'p'     00-0F   linux/phantom.h         conflict! (OpenHaptics needs this)
 250'p'     00-1F   linux/rtc.h             conflict!
 251'p'     00-3F   linux/mc146818rtc.h     conflict!
 252'p'     40-7F   linux/nvram.h
 253'p'     80-9F   linux/ppdev.h           user-space parport
 254                                        <>
 255'p'     A1-A5   linux/pps.h             LinuxPPS
 256                                        <>
 257'q'     00-1F   linux/serio.h
 258'q'     80-FF   linux/telephony.h       Internet PhoneJACK, Internet LineJACK
 259                linux/ixjuser.h         <*/>
 260'r'     00-1F   linux/msdos_fs.h and fs/fat/dir.c
 261's'     all     linux/cdk.h
 262't'     00-7F   linux/ppp-ioctl.h
 263't'     80-8F   linux/isdn_ppp.h
 264't'     90      linux/toshiba.h
 265'u'     00-1F   linux/smb_fs.h          gone
 266'u'     20-3F   linux/uvcvideo.h        USB video class host driver
 267'v'     00-1F   linux/ext2_fs.h         conflict!
 268'v'     00-1F   linux/fs.h              conflict!
 269'v'     00-0F   linux/sonypi.h          conflict!
 270'v'     C0-DF   media/pwc-ioctl.h       conflict!
 271'v'     C0-FF   linux/meye.h            conflict!
 272'v'     D0-DF   drivers/media/video/cpia2/cpia2dev.h    conflict!
 273'w'     all                             CERN SCI driver
 274'y'     00-1F                           packet based user level communications
 275                                        <>
 276'z'     00-3F                           CAN bus card    conflict!
 277                                        <>
 278'z'     40-7F                           CAN bus card    conflict!
 279                                        <>
 280'z'     10-4F   drivers/s390/crypto/zcrypt_api.h        conflict!
 281'|'     00-7F   linux/media.h
 2820x80    00-1F   linux/fb.h
 2830x89    00-06   arch/x86/include/asm/sockios.h
 2840x89    0B-DF   linux/sockios.h
 2850x89    E0-EF   linux/sockios.h         SIOCPROTOPRIVATE range
 2860x89    E0-EF   linux/dn.h              PROTOPRIVATE range
 2870x89    F0-FF   linux/sockios.h         SIOCDEVPRIVATE range
 2880x8B    all     linux/wireless.h
 2890x8C    00-3F                           WiNRADiO driver
 290                                        <>
 2910x90    00      drivers/cdrom/sbpcd.h
 2920x92    00-0F   drivers/usb/mon/mon_bin.c
 2930x93    60-7F   linux/auto_fs.h
 2940x94    all     fs/btrfs/ioctl.h
 2950x97    00-7F   fs/ceph/ioctl.h         Ceph file system
 2960x99    00-0F                           537-Addinboard driver
 297                                        <>
 2980xA0    all     linux/sdp/sdp.h         Industrial Device Project
 299                                        <>
 3000xA2    00-0F   arch/tile/include/asm/hardwall.h
 3010xA3    80-8F   Port ACL                in development:
 302                                        <>
 3030xA3    90-9F   linux/dtlk.h
 3040xAB    00-1F   linux/nbd.h
 3050xAC    00-1F   linux/raw.h
 3060xAD    00      Netfilter device        in development:
 307                                        <>
 3080xAE    all     linux/kvm.h             Kernel-based Virtual Machine
 309                                        <>
 3100xAF    00-1F   linux/fsl_hypervisor.h  Freescale hypervisor
 3110xB0    all     RATIO devices           in development:
 312                                        <>
 3130xB1    00-1F   PPPoX                   <>
 3140xB3    00      linux/mmc/ioctl.h
 3150xC0    00-0F   linux/usb/iowarrior.h
 3160xCB    00-1F   CBM serial IEC bus      in development:
 317                                        <>
 3180xCD    01      linux/reiserfs_fs.h
 3190xCF    02      fs/cifs/ioctl.c
 3200xDB    00-0F   drivers/char/mwave/mwavepub.h
 3210xDD    00-3F   ZFCP device driver      see drivers/s390/scsi/
 322                                        <>
 3230xF3    00-3F   drivers/usb/misc/sisusbvga/sisusb.h     sisfb (in development)
 324                                        <>
 3250xF4    00-1F   video/mbxfb.h           mbxfb
 326                                        <>
 3270xF6    all     LTTng                   Linux Trace Toolkit Next Generation
 328                                        <>
 3290xFD    all     linux/dm-ioctl.h
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