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
  750x10    10-1F   arch/s390/include/uapi/sclp_ctl.h
  760x12    all     linux/fs.h
  77                linux/blkpg.h
  780x1b    all     InfiniBand Subsystem    <>
  790x20    all     drivers/cdrom/cm206.h
  800x22    all     scsi/sg.h
  81'#'     00-3F   IEEE 1394 Subsystem     Block for the entire subsystem
  82'$'     00-0F   linux/perf_counter.h, linux/perf_event.h
  83'&'     00-07   drivers/firewire/nosy-user.h
  84'1'     00-1F   <linux/timepps.h>       PPS kit from Ulrich Windl
  85                                        <>
  86'2'     01-04   linux/i2o.h
  87'3'     00-0F   drivers/s390/char/raw3270.h     conflict!
  88'3'     00-1F   linux/suspend_ioctls.h  conflict!
  89                and kernel/power/user.c
  90'8'     all                             SNP8023 advanced NIC card
  91                                        <>
  92';'     64-7F   linux/vfio.h
  93'@'     00-0F   linux/radeonfb.h        conflict!
  94'@'     00-0F   drivers/video/aty/aty128fb.c    conflict!
  95'A'     00-1F   linux/apm_bios.h        conflict!
  96'A'     00-0F   linux/agpgart.h         conflict!
  97                and drivers/char/agp/compat_ioctl.h
  98'A'     00-7F   sound/asound.h          conflict!
  99'B'     00-1F   linux/cciss_ioctl.h     conflict!
 100'B'     00-0F   include/linux/pmu.h     conflict!
 101'B'     C0-FF                           advanced bbus
 102                                        <>
 103'C'     all     linux/soundcard.h       conflict!
 104'C'     01-2F   linux/capi.h            conflict!
 105'C'     F0-FF   drivers/net/wan/cosa.h  conflict!
 106'D'     all     arch/s390/include/asm/dasd.h
 107'D'     40-5F   drivers/scsi/dpt/dtpi_ioctl.h
 108'D'     05      drivers/scsi/pmcraid.h
 109'E'     all     linux/input.h           conflict!
 110'E'     00-0F   xen/evtchn.h            conflict!
 111'F'     all     linux/fb.h              conflict!
 112'F'     01-02   drivers/scsi/pmcraid.h  conflict!
 113'F'     20      drivers/video/fsl-diu-fb.h      conflict!
 114'F'     20      drivers/video/intelfb/intelfb.h conflict!
 115'F'     20      linux/ivtvfb.h          conflict!
 116'F'     20      linux/matroxfb.h        conflict!
 117'F'     20      drivers/video/aty/atyfb_base.c  conflict!
 118'F'     00-0F   video/da8xx-fb.h        conflict!
 119'F'     80-8F   linux/arcfb.h           conflict!
 120'F'     DD      video/sstfb.h           conflict!
 121'G'     00-3F   drivers/misc/sgi-gru/grulib.h   conflict!
 122'G'     00-0F   linux/gigaset_dev.h     conflict!
 123'H'     00-7F   linux/hiddev.h          conflict!
 124'H'     00-0F   linux/hidraw.h          conflict!
 125'H'     01      linux/mei.h             conflict!
 126'H'     00-0F   sound/asound.h          conflict!
 127'H'     20-40   sound/asound_fm.h       conflict!
 128'H'     80-8F   sound/sfnt_info.h       conflict!
 129'H'     10-8F   sound/emu10k1.h         conflict!
 130'H'     10-1F   sound/sb16_csp.h        conflict!
 131'H'     10-1F   sound/hda_hwdep.h       conflict!
 132'H'     40-4F   sound/hdspm.h           conflict!
 133'H'     40-4F   sound/hdsp.h            conflict!
 134'H'     90      sound/usb/usx2y/usb_stream.h
 135'H'     A0      uapi/linux/usb/cdc-wdm.h
 136'H'     C0-F0   net/bluetooth/hci.h     conflict!
 137'H'     C0-DF   net/bluetooth/hidp/hidp.h       conflict!
 138'H'     C0-DF   net/bluetooth/cmtp/cmtp.h       conflict!
 139'H'     C0-DF   net/bluetooth/bnep/bnep.h       conflict!
 140'H'     F1      linux/hid-roccat.h      <>
 141'I'     all     linux/isdn.h            conflict!
 142'I'     00-0F   drivers/isdn/divert/isdn_divert.h       conflict!
 143'I'     40-4F   linux/mISDNif.h         conflict!
 144'J'     00-1F   drivers/scsi/gdth_ioctl.h
 145'K'     all     linux/kd.h
 146'L'     00-1F   linux/loop.h            conflict!
 147'L'     10-1F   drivers/scsi/mpt2sas/mpt2sas_ctl.h      conflict!
 148'L'     E0-FF   linux/ppdd.h            encrypted disk device driver
 149                                        <>
 150'M'     all     linux/soundcard.h       conflict!
 151'M'     01-16   mtd/mtd-abi.h           conflict!
 152                and drivers/mtd/mtdchar.c
 153'M'     01-03   drivers/scsi/megaraid/megaraid_sas.h
 154'M'     00-0F   drivers/video/fsl-diu-fb.h      conflict!
 155'N'     00-1F   drivers/usb/scanner.h
 156'N'     40-7F   drivers/block/nvme.c
 157'O'     00-06   mtd/ubi-user.h          UBI
 158'P'     all     linux/soundcard.h       conflict!
 159'P'     60-6F   sound/sscape_ioctl.h    conflict!
 160'P'     00-0F   drivers/usb/class/usblp.c       conflict!
 161'Q'     all     linux/soundcard.h
 162'R'     00-1F   linux/random.h          conflict!
 163'R'     01      linux/rfkill.h          conflict!
 164'R'     C0-DF   net/bluetooth/rfcomm.h
 165'S'     all     linux/cdrom.h           conflict!
 166'S'     80-81   scsi/scsi_ioctl.h       conflict!
 167'S'     82-FF   scsi/scsi.h             conflict!
 168'S'     00-7F   sound/asequencer.h      conflict!
 169'T'     all     linux/soundcard.h       conflict!
 170'T'     00-AF   sound/asound.h          conflict!
 171'T'     all     arch/x86/include/asm/ioctls.h   conflict!
 172'T'     C0-DF   linux/if_tun.h          conflict!
 173'U'     all     sound/asound.h          conflict!
 174'U'     00-CF   linux/uinput.h          conflict!
 175'U'     00-EF   linux/usbdevice_fs.h
 176'U'     C0-CF   drivers/bluetooth/hci_uart.h
 177'V'     all     linux/vt.h              conflict!
 178'V'     all     linux/videodev2.h       conflict!
 179'V'     C0      linux/ivtvfb.h          conflict!
 180'V'     C0      linux/ivtv.h            conflict!
 181'V'     C0      media/davinci/vpfe_capture.h    conflict!
 182'V'     C0      media/si4713.h          conflict!
 183'W'     00-1F   linux/watchdog.h        conflict!
 184'W'     00-1F   linux/wanrouter.h       conflict!               (pre 3.9)
 185'W'     00-3F   sound/asound.h          conflict!
 186'X'     all     fs/xfs/xfs_fs.h         conflict!
 187                and fs/xfs/linux-2.6/xfs_ioctl32.h
 188                and include/linux/falloc.h
 189                and linux/fs.h
 190'X'     all     fs/ocfs2/ocfs_fs.h      conflict!
 191'X'     01      linux/pktcdvd.h         conflict!
 192'Y'     all     linux/cyclades.h
 193'Z'     14-15   drivers/message/fusion/mptctl.h
 194'['     00-07   linux/usb/tmc.h         USB Test and Measurement Devices
 195                                        <>
 196'a'     all     linux/atm*.h, linux/sonet.h     ATM on linux
 197                                        <>
 198'b'     00-FF                           conflict! bit3 vme host bridge
 199                                        <>
 200'c'     all     linux/cm4000_cs.h       conflict!
 201'c'     00-7F   linux/comstats.h        conflict!
 202'c'     00-7F   linux/coda.h            conflict!
 203'c'     00-1F   linux/chio.h            conflict!
 204'c'     80-9F   arch/s390/include/asm/chsc.h    conflict!
 205'c'     A0-AF   arch/x86/include/asm/msr.h      conflict!
 206'd'     00-FF   linux/char/drm/drm/h    conflict!
 207'd'     02-40   pcmcia/ds.h             conflict!
 208'd'     F0-FF   linux/digi1.h
 209'e'     all     linux/digi1.h           conflict!
 210'e'     00-1F   drivers/net/irda/irtty-sir.h    conflict!
 211'f'     00-1F   linux/ext2_fs.h         conflict!
 212'f'     00-1F   linux/ext3_fs.h         conflict!
 213'f'     00-0F   fs/jfs/jfs_dinode.h     conflict!
 214'f'     00-0F   fs/ext4/ext4.h          conflict!
 215'f'     00-0F   linux/fs.h              conflict!
 216'f'     00-0F   fs/ocfs2/ocfs2_fs.h     conflict!
 217'g'     00-0F   linux/usb/gadgetfs.h
 218'g'     20-2F   linux/usb/g_printer.h
 219'h'     00-7F                           conflict! Charon filesystem
 220                                        <>
 221'h'     00-1F   linux/hpet.h            conflict!
 222'h'     80-8F   fs/hfsplus/ioctl.c
 223'i'     00-3F   linux/i2o-dev.h         conflict!
 224'i'     0B-1F   linux/ipmi.h            conflict!
 225'i'     80-8F   linux/i8k.h
 226'j'     00-3F   linux/joystick.h
 227'k'     00-0F   linux/spi/spidev.h      conflict!
 228'k'     00-05   video/kyro.h            conflict!
 229'k'     10-17   linux/hsi/hsi_char.h    HSI character device
 230'l'     00-3F   linux/tcfs_fs.h         transparent cryptographic file system
 231                                        <*/>
 232'l'     40-7F   linux/udf_fs_i.h        in development:
 233                                        <>
 234'm'     00-09   linux/mmtimer.h         conflict!
 235'm'     all     linux/mtio.h            conflict!
 236'm'     all     linux/soundcard.h       conflict!
 237'm'     all     linux/synclink.h        conflict!
 238'm'     00-19   drivers/message/fusion/mptctl.h conflict!
 239'm'     00      drivers/scsi/megaraid/megaraid_ioctl.h  conflict!
 240'm'     00-1F   net/irda/irmod.h        conflict!
 241'n'     00-7F   linux/ncp_fs.h and fs/ncpfs/ioctl.c
 242'n'     80-8F   linux/nilfs2_fs.h       NILFS2
 243'n'     E0-FF   linux/matroxfb.h        matroxfb
 244'o'     00-1F   fs/ocfs2/ocfs2_fs.h     OCFS2
 245'o'     00-03   mtd/ubi-user.h          conflict! (OCFS2 and UBI overlaps)
 246'o'     40-41   mtd/ubi-user.h          UBI
 247'o'     01-A1   linux/dvb/*.h           DVB
 248'p'     00-0F   linux/phantom.h         conflict! (OpenHaptics needs this)
 249'p'     00-1F   linux/rtc.h             conflict!
 250'p'     00-3F   linux/mc146818rtc.h     conflict!
 251'p'     40-7F   linux/nvram.h
 252'p'     80-9F   linux/ppdev.h           user-space parport
 253                                        <>
 254'p'     A1-A5   linux/pps.h             LinuxPPS
 255                                        <>
 256'q'     00-1F   linux/serio.h
 257'q'     80-FF   linux/telephony.h       Internet PhoneJACK, Internet LineJACK
 258                linux/ixjuser.h         <*/>
 259'r'     00-1F   linux/msdos_fs.h and fs/fat/dir.c
 260's'     all     linux/cdk.h
 261't'     00-7F   linux/ppp-ioctl.h
 262't'     80-8F   linux/isdn_ppp.h
 263't'     90      linux/toshiba.h
 264'u'     00-1F   linux/smb_fs.h          gone
 265'u'     20-3F   linux/uvcvideo.h        USB video class host driver
 266'v'     00-1F   linux/ext2_fs.h         conflict!
 267'v'     00-1F   linux/fs.h              conflict!
 268'v'     00-0F   linux/sonypi.h          conflict!
 269'v'     C0-FF   linux/meye.h            conflict!
 270'w'     all                             CERN SCI driver
 271'y'     00-1F                           packet based user level communications
 272                                        <>
 273'z'     00-3F                           CAN bus card    conflict!
 274                                        <>
 275'z'     40-7F                           CAN bus card    conflict!
 276                                        <>
 277'z'     10-4F   drivers/s390/crypto/zcrypt_api.h        conflict!
 278'|'     00-7F   linux/media.h
 2790x80    00-1F   linux/fb.h
 2800x89    00-06   arch/x86/include/asm/sockios.h
 2810x89    0B-DF   linux/sockios.h
 2820x89    E0-EF   linux/sockios.h         SIOCPROTOPRIVATE range
 2830x89    E0-EF   linux/dn.h              PROTOPRIVATE range
 2840x89    F0-FF   linux/sockios.h         SIOCDEVPRIVATE range
 2850x8B    all     linux/wireless.h
 2860x8C    00-3F                           WiNRADiO driver
 287                                        <>
 2880x90    00      drivers/cdrom/sbpcd.h
 2890x92    00-0F   drivers/usb/mon/mon_bin.c
 2900x93    60-7F   linux/auto_fs.h
 2910x94    all     fs/btrfs/ioctl.h
 2920x97    00-7F   fs/ceph/ioctl.h         Ceph file system
 2930x99    00-0F                           537-Addinboard driver
 294                                        <>
 2950xA0    all     linux/sdp/sdp.h         Industrial Device Project
 296                                        <>
 2970xA2    00-0F   arch/tile/include/asm/hardwall.h
 2980xA3    80-8F   Port ACL                in development:
 299                                        <>
 3000xA3    90-9F   linux/dtlk.h
 3010xAB    00-1F   linux/nbd.h
 3020xAC    00-1F   linux/raw.h
 3030xAD    00      Netfilter device        in development:
 304                                        <>
 3050xAE    all     linux/kvm.h             Kernel-based Virtual Machine
 306                                        <>
 3070xAF    00-1F   linux/fsl_hypervisor.h  Freescale hypervisor
 3080xB0    all     RATIO devices           in development:
 309                                        <>
 3100xB1    00-1F   PPPoX                   <>
 3110xB3    00      linux/mmc/ioctl.h
 3120xC0    00-0F   linux/usb/iowarrior.h
 3130xCB    00-1F   CBM serial IEC bus      in development:
 314                                        <>
 3150xCD    01      linux/reiserfs_fs.h
 3160xCF    02      fs/cifs/ioctl.c
 3170xDB    00-0F   drivers/char/mwave/mwavepub.h
 3180xDD    00-3F   ZFCP device driver      see drivers/s390/scsi/
 319                                        <>
 3200xF3    00-3F   drivers/usb/misc/sisusbvga/sisusb.h     sisfb (in development)
 321                                        <>
 3220xF4    00-1F   video/mbxfb.h           mbxfb
 323                                        <>
 3240xF6    all     LTTng                   Linux Trace Toolkit Next Generation
 325                                        <>
 3260xFD    all     linux/dm-ioctl.h