1Ioctl Numbers 219 October 1999 3Michael Elizabeth Chastain 4<mec@shout.net> 5 6If you are adding new ioctl's to the kernel, you should use the _IO 7macros defined in <linux/ioctl.h>: 8 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. 13 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. 19 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. 23 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 <mec@shout.net> and 28I'll register one for you. 29 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. 36 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. 40 41Following this convention is good because: 42 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. 46 47(2) The 'strace' build procedure automatically finds ioctl numbers 48 defined with _IO, _IOW, _IOR, or _IOWR. 49 50(3) 'strace' can decode numbers back into useful names when the 51 numbers are unique. 52 53(4) People looking for ioctls can grep for them more easily when 54 this convention is used to define the ioctl numbers. 55 56(5) When following the convention, the driver code can use generic 57 code to copy the parameters between user and kernel space. 58 59This table lists ioctls visible from user land for Linux/i386. It contains 60most drivers up to 2.3.14, but I know I am missing some. 61 62Code Seq# Include File Comments 63======================================================== 640x00 00-1F linux/fs.h conflict! 650x00 00-1F scsi/scsi_ioctl.h conflict! 660x00 00-1F linux/fb.h conflict! 670x00 00-1F linux/wavefront.h conflict! 680x02 all linux/fd.h 690x03 all linux/hdreg.h 700x04 D2-DC linux/umsdos_fs.h Dead since 2.6.11, but don't reuse these. 710x06 all linux/lp.h 720x09 all linux/md.h 730x12 all linux/fs.h 74 linux/blkpg.h 750x1b all InfiniBand Subsystem <http://www.openib.org/> 760x20 all drivers/cdrom/cm206.h 770x22 all scsi/sg.h 78'#' 00-3F IEEE 1394 Subsystem Block for the entire subsystem 79'1' 00-1F <linux/timepps.h> PPS kit from Ulrich Windl 80 <ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/> 81'8' all SNP8023 advanced NIC card 82 <mailto:mcr@solidum.com> 83'A' 00-1F linux/apm_bios.h 84'B' C0-FF advanced bbus 85 <mailto:maassen@uni-freiburg.de> 86'C' all linux/soundcard.h 87'D' all arch/s390/include/asm/dasd.h 88'E' all linux/input.h 89'F' all linux/fb.h 90'H' all linux/hiddev.h 91'I' all linux/isdn.h 92'J' 00-1F drivers/scsi/gdth_ioctl.h 93'K' all linux/kd.h 94'L' 00-1F linux/loop.h 95'L' 20-2F driver/usb/misc/vstusb.h 96'L' E0-FF linux/ppdd.h encrypted disk device driver 97 <http://linux01.gwdg.de/~alatham/ppdd.html> 98'M' all linux/soundcard.h 99'N' 00-1F drivers/usb/scanner.h 100'O' 00-02 include/mtd/ubi-user.h UBI 101'P' all linux/soundcard.h 102'Q' all linux/soundcard.h 103'R' 00-1F linux/random.h 104'S' all linux/cdrom.h conflict! 105'S' 80-81 scsi/scsi_ioctl.h conflict! 106'S' 82-FF scsi/scsi.h conflict! 107'T' all linux/soundcard.h conflict! 108'T' all arch/x86/include/asm/ioctls.h conflict! 109'U' 00-EF linux/drivers/usb/usb.h 110'V' all linux/vt.h 111'W' 00-1F linux/watchdog.h conflict! 112'W' 00-1F linux/wanrouter.h conflict! 113'X' all linux/xfs_fs.h 114'Y' all linux/cyclades.h 115'[' 00-07 linux/usb/usbtmc.h USB Test and Measurement Devices 116 <mailto:gregkh@suse.de> 117'a' all ATM on linux 118 <http://lrcwww.epfl.ch/linux-atm/magic.html> 119'b' 00-FF bit3 vme host bridge 120 <mailto:natalia@nikhefk.nikhef.nl> 121'c' 00-7F linux/comstats.h conflict! 122'c' 00-7F linux/coda.h conflict! 123'c' 80-9F arch/s390/include/asm/chsc.h 124'c' A0-AF arch/x86/include/asm/msr.h 125'd' 00-FF linux/char/drm/drm/h conflict! 126'd' F0-FF linux/digi1.h 127'e' all linux/digi1.h conflict! 128'e' 00-1F net/irda/irtty.h conflict! 129'f' 00-1F linux/ext2_fs.h 130'h' 00-7F Charon filesystem 131 <mailto:zapman@interlan.net> 132'i' 00-3F linux/i2o.h 133'j' 00-3F linux/joystick.h 134'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system 135 <http://mikonos.dia.unisa.it/tcfs> 136'l' 40-7F linux/udf_fs_i.h in development: 137 <http://sourceforge.net/projects/linux-udf/> 138'm' 00-09 linux/mmtimer.h 139'm' all linux/mtio.h conflict! 140'm' all linux/soundcard.h conflict! 141'm' all linux/synclink.h conflict! 142'm' 00-1F net/irda/irmod.h conflict! 143'n' 00-7F linux/ncp_fs.h 144'n' 80-8F linux/nilfs2_fs.h NILFS2 145'n' E0-FF video/matrox.h matroxfb 146'o' 00-1F fs/ocfs2/ocfs2_fs.h OCFS2 147'o' 00-03 include/mtd/ubi-user.h conflict! (OCFS2 and UBI overlaps) 148'o' 40-41 include/mtd/ubi-user.h UBI 149'o' 01-A1 include/linux/dvb/*.h DVB 150'p' 00-0F linux/phantom.h conflict! (OpenHaptics needs this) 151'p' 00-3F linux/mc146818rtc.h conflict! 152'p' 40-7F linux/nvram.h 153'p' 80-9F user-space parport 154 <mailto:tim@cyberelk.net> 155'p' a1-a4 linux/pps.h LinuxPPS 156 <mailto:giometti@linux.it> 157'q' 00-1F linux/serio.h 158'q' 80-FF Internet PhoneJACK, Internet LineJACK 159 <http://www.quicknet.net> 160'r' 00-1F linux/msdos_fs.h 161's' all linux/cdk.h 162't' 00-7F linux/if_ppp.h 163't' 80-8F linux/isdn_ppp.h 164'u' 00-1F linux/smb_fs.h 165'v' 00-1F linux/ext2_fs.h conflict! 166'v' all linux/videodev.h conflict! 167'w' all CERN SCI driver 168'y' 00-1F packet based user level communications 169 <mailto:zapman@interlan.net> 170'z' 00-3F CAN bus card 171 <mailto:hdstich@connectu.ulm.circular.de> 172'z' 40-7F CAN bus card 173 <mailto:oe@port.de> 1740x80 00-1F linux/fb.h 1750x81 00-1F linux/videotext.h 1760x89 00-06 arch/x86/include/asm/sockios.h 1770x89 0B-DF linux/sockios.h 1780x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range 1790x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range 1800x8B all linux/wireless.h 1810x8C 00-3F WiNRADiO driver 182 <http://www.proximity.com.au/~brian/winradio/> 1830x90 00 drivers/cdrom/sbpcd.h 1840x93 60-7F linux/auto_fs.h 1850x99 00-0F 537-Addinboard driver 186 <mailto:buk@buks.ipn.de> 1870xA0 all linux/sdp/sdp.h Industrial Device Project 188 <mailto:kenji@bitgate.com> 1890xA3 80-8F Port ACL in development: 190 <mailto:tlewis@mindspring.com> 1910xA3 90-9F linux/dtlk.h 1920xAB 00-1F linux/nbd.h 1930xAC 00-1F linux/raw.h 1940xAD 00 Netfilter device in development: 195 <mailto:rusty@rustcorp.com.au> 1960xAE all linux/kvm.h Kernel-based Virtual Machine 197 <mailto:kvm@vger.kernel.org> 1980xB0 all RATIO devices in development: 199 <mailto:vgo@ratio.de> 2000xB1 00-1F PPPoX <mailto:mostrows@styx.uwaterloo.ca> 2010xCB 00-1F CBM serial IEC bus in development: 202 <mailto:michael.klein@puffin.lb.shuttle.de> 2030xDD 00-3F ZFCP device driver see drivers/s390/scsi/ 204 <mailto:aherrman@de.ibm.com> 2050xF3 00-3F video/sisfb.h sisfb (in development) 206 <mailto:thomas@winischhofer.net> 2070xF4 00-1F video/mbxfb.h mbxfb 208 <mailto:raph@8d.com> 209