| Ioctl Numbers |
| 19 October 1999 |
| Michael Elizabeth Chastain |
| <mec@shout.net> |
| |
| If you are adding new ioctl's to the kernel, you should use the _IO |
| macros defined in <linux/ioctl.h>: |
| |
| _IO an ioctl with no parameters |
| _IOW an ioctl with write parameters (copy_from_user) |
| _IOR an ioctl with read parameters (copy_to_user) |
| _IOWR an ioctl with both write and read parameters. |
| |
| 'Write' and 'read' are from the user's point of view, just like the |
| system calls 'write' and 'read'. For example, a SET_FOO ioctl would |
| be _IOW, although the kernel would actually read data from user space; |
| a GET_FOO ioctl would be _IOR, although the kernel would actually write |
| data to user space. |
| |
| The first argument to _IO, _IOW, _IOR, or _IOWR is an identifying letter |
| or number from the table below. Because of the large number of drivers, |
| many drivers share a partial letter with other drivers. |
| |
| If you are writing a driver for a new device and need a letter, pick an |
| unused block with enough room for expansion: 32 to 256 ioctl commands. |
| You can register the block by patching this file and submitting the |
| patch to Linus Torvalds. Or you can e-mail me at <mec@shout.net> and |
| I'll register one for you. |
| |
| The second argument to _IO, _IOW, _IOR, or _IOWR is a sequence number |
| to distinguish ioctls from each other. The third argument to _IOW, |
| _IOR, or _IOWR is the type of the data going into the kernel or coming |
| out of the kernel (e.g. 'int' or 'struct foo'). NOTE! Do NOT use |
| sizeof(arg) as the third argument as this results in your ioctl thinking |
| it passes an argument of type size_t. |
| |
| Some devices use their major number as the identifier; this is OK, as |
| long as it is unique. Some devices are irregular and don't follow any |
| convention at all. |
| |
| Following this convention is good because: |
| |
| (1) Keeping the ioctl's globally unique helps error checking: |
| if a program calls an ioctl on the wrong device, it will get an |
| error rather than some unexpected behaviour. |
| |
| (2) The 'strace' build procedure automatically finds ioctl numbers |
| defined with _IO, _IOW, _IOR, or _IOWR. |
| |
| (3) 'strace' can decode numbers back into useful names when the |
| numbers are unique. |
| |
| (4) People looking for ioctls can grep for them more easily when |
| this convention is used to define the ioctl numbers. |
| |
| (5) When following the convention, the driver code can use generic |
| code to copy the parameters between user and kernel space. |
| |
| This table lists ioctls visible from user land for Linux/i386. It contains |
| most drivers up to 2.3.14, but I know I am missing some. |
| |
| Code Seq# Include File Comments |
| ======================================================== |
| 0x00 00-1F linux/fs.h conflict! |
| 0x00 00-1F scsi/scsi_ioctl.h conflict! |
| 0x00 00-1F linux/fb.h conflict! |
| 0x00 00-1F linux/wavefront.h conflict! |
| 0x02 all linux/fd.h |
| 0x03 all linux/hdreg.h |
| 0x04 D2-DC linux/umsdos_fs.h Dead since 2.6.11, but don't reuse these. |
| 0x06 all linux/lp.h |
| 0x09 all linux/md.h |
| 0x12 all linux/fs.h |
| linux/blkpg.h |
| 0x1b all InfiniBand Subsystem <http://www.openib.org/> |
| 0x20 all drivers/cdrom/cm206.h |
| 0x22 all scsi/sg.h |
| '#' 00-3F IEEE 1394 Subsystem Block for the entire subsystem |
| '1' 00-1F <linux/timepps.h> PPS kit from Ulrich Windl |
| <ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/> |
| '8' all SNP8023 advanced NIC card |
| <mailto:mcr@solidum.com> |
| 'A' 00-1F linux/apm_bios.h |
| 'B' C0-FF advanced bbus |
| <mailto:maassen@uni-freiburg.de> |
| 'C' all linux/soundcard.h |
| 'D' all arch/s390/include/asm/dasd.h |
| 'E' all linux/input.h |
| 'F' all linux/fb.h |
| 'H' all linux/hiddev.h |
| 'I' all linux/isdn.h |
| 'J' 00-1F drivers/scsi/gdth_ioctl.h |
| 'K' all linux/kd.h |
| 'L' 00-1F linux/loop.h |
| 'L' 20-2F driver/usb/misc/vstusb.h |
| 'L' E0-FF linux/ppdd.h encrypted disk device driver |
| <http://linux01.gwdg.de/~alatham/ppdd.html> |
| 'M' all linux/soundcard.h |
| 'N' 00-1F drivers/usb/scanner.h |
| 'O' 00-02 include/mtd/ubi-user.h UBI |
| 'P' all linux/soundcard.h |
| 'Q' all linux/soundcard.h |
| 'R' 00-1F linux/random.h |
| 'S' all linux/cdrom.h conflict! |
| 'S' 80-81 scsi/scsi_ioctl.h conflict! |
| 'S' 82-FF scsi/scsi.h conflict! |
| 'T' all linux/soundcard.h conflict! |
| 'T' all arch/x86/include/asm/ioctls.h conflict! |
| 'U' 00-EF linux/drivers/usb/usb.h |
| 'V' all linux/vt.h |
| 'W' 00-1F linux/watchdog.h conflict! |
| 'W' 00-1F linux/wanrouter.h conflict! |
| 'X' all linux/xfs_fs.h |
| 'Y' all linux/cyclades.h |
| '[' 00-07 linux/usb/usbtmc.h USB Test and Measurement Devices |
| <mailto:gregkh@suse.de> |
| 'a' all ATM on linux |
| <http://lrcwww.epfl.ch/linux-atm/magic.html> |
| 'b' 00-FF bit3 vme host bridge |
| <mailto:natalia@nikhefk.nikhef.nl> |
| 'c' 00-7F linux/comstats.h conflict! |
| 'c' 00-7F linux/coda.h conflict! |
| 'c' 80-9F arch/s390/include/asm/chsc.h |
| 'd' 00-FF linux/char/drm/drm/h conflict! |
| 'd' 00-DF linux/video_decoder.h conflict! |
| 'd' F0-FF linux/digi1.h |
| 'e' all linux/digi1.h conflict! |
| 'e' 00-1F linux/video_encoder.h conflict! |
| 'e' 00-1F net/irda/irtty.h conflict! |
| 'f' 00-1F linux/ext2_fs.h |
| 'h' 00-7F Charon filesystem |
| <mailto:zapman@interlan.net> |
| 'i' 00-3F linux/i2o.h |
| 'j' 00-3F linux/joystick.h |
| 'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system |
| <http://mikonos.dia.unisa.it/tcfs> |
| 'l' 40-7F linux/udf_fs_i.h in development: |
| <http://sourceforge.net/projects/linux-udf/> |
| 'm' all linux/mtio.h conflict! |
| 'm' all linux/soundcard.h conflict! |
| 'm' all linux/synclink.h conflict! |
| 'm' 00-1F net/irda/irmod.h conflict! |
| 'n' 00-7F linux/ncp_fs.h |
| 'n' E0-FF video/matrox.h matroxfb |
| 'o' 00-1F fs/ocfs2/ocfs2_fs.h OCFS2 |
| 'o' 00-03 include/mtd/ubi-user.h conflict! (OCFS2 and UBI overlaps) |
| 'o' 40-41 include/mtd/ubi-user.h UBI |
| 'o' 01-A1 include/linux/dvb/*.h DVB |
| 'p' 00-0F linux/phantom.h conflict! (OpenHaptics needs this) |
| 'p' 00-3F linux/mc146818rtc.h conflict! |
| 'p' 40-7F linux/nvram.h |
| 'p' 80-9F user-space parport |
| <mailto:tim@cyberelk.net> |
| 'q' 00-1F linux/serio.h |
| 'q' 80-FF Internet PhoneJACK, Internet LineJACK |
| <http://www.quicknet.net> |
| 'r' 00-1F linux/msdos_fs.h |
| 's' all linux/cdk.h |
| 't' 00-7F linux/if_ppp.h |
| 't' 80-8F linux/isdn_ppp.h |
| 'u' 00-1F linux/smb_fs.h |
| 'v' 00-1F linux/ext2_fs.h conflict! |
| 'v' all linux/videodev.h conflict! |
| 'w' all CERN SCI driver |
| 'y' 00-1F packet based user level communications |
| <mailto:zapman@interlan.net> |
| 'z' 00-3F CAN bus card |
| <mailto:hdstich@connectu.ulm.circular.de> |
| 'z' 40-7F CAN bus card |
| <mailto:oe@port.de> |
| 0x80 00-1F linux/fb.h |
| 0x81 00-1F linux/videotext.h |
| 0x89 00-06 arch/x86/include/asm/sockios.h |
| 0x89 0B-DF linux/sockios.h |
| 0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range |
| 0x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range |
| 0x8B all linux/wireless.h |
| 0x8C 00-3F WiNRADiO driver |
| <http://www.proximity.com.au/~brian/winradio/> |
| 0x90 00 drivers/cdrom/sbpcd.h |
| 0x93 60-7F linux/auto_fs.h |
| 0x99 00-0F 537-Addinboard driver |
| <mailto:buk@buks.ipn.de> |
| 0xA0 all linux/sdp/sdp.h Industrial Device Project |
| <mailto:kenji@bitgate.com> |
| 0xA3 80-8F Port ACL in development: |
| <mailto:tlewis@mindspring.com> |
| 0xA3 90-9F linux/dtlk.h |
| 0xAB 00-1F linux/nbd.h |
| 0xAC 00-1F linux/raw.h |
| 0xAD 00 Netfilter device in development: |
| <mailto:rusty@rustcorp.com.au> |
| 0xAE all linux/kvm.h Kernel-based Virtual Machine |
| <mailto:kvm-devel@lists.sourceforge.net> |
| 0xB0 all RATIO devices in development: |
| <mailto:vgo@ratio.de> |
| 0xB1 00-1F PPPoX <mailto:mostrows@styx.uwaterloo.ca> |
| 0xCB 00-1F CBM serial IEC bus in development: |
| <mailto:michael.klein@puffin.lb.shuttle.de> |
| 0xDD 00-3F ZFCP device driver see drivers/s390/scsi/ |
| <mailto:aherrman@de.ibm.com> |
| 0xF3 00-3F video/sisfb.h sisfb (in development) |
| <mailto:thomas@winischhofer.net> |
| 0xF4 00-1F video/mbxfb.h mbxfb |
| <mailto:raph@8d.com> |