=============
Ioctl Numbers
=============
19 October 1999
Michael Elizabeth Chastain
<[email protected]>
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 <[email protected]> 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/x86. It contains
most drivers up to 2.6.31, but I know I am missing some. There has been
no attempt to list non-X86 architectures or ioctls from drivers/staging/.
==== ===== ======================================================= ================================================================
Code Seq# Include File Comments
(hex)
==== ===== ======================================================= ================================================================
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
0x07 9F-D0 linux/vmw_vmci_defs.h, uapi/linux/vm_sockets.h
0x09 all linux/raid/md_u.h
0x10 00-0F drivers/char/s390/vmcp.h
0x10 10-1F arch/s390/include/uapi/sclp_ctl.h
0x10 20-2F arch/s390/include/uapi/asm/hypfs.h
0x12 all linux/fs.h BLK* ioctls
linux/blkpg.h
0x15 all linux/fs.h FS_IOC_* ioctls
0x1b all InfiniBand Subsystem
<http://infiniband.sourceforge.net/>
0x20 all drivers/cdrom/cm206.h
0x22 all scsi/sg.h
0x3E 00-0F linux/counter.h <mailto:[email protected]>
'!' 00-1F uapi/linux/seccomp.h
'#' 00-3F IEEE 1394 Subsystem
Block for the entire subsystem
'$' 00-0F linux/perf_counter.h, linux/perf_event.h
'%' 00-0F include/uapi/linux/stm.h System Trace Module subsystem
<mailto:[email protected]>
'&' 00-07 drivers/firewire/nosy-user.h
'*' 00-1F uapi/linux/user_events.h User Events Subsystem
<mailto:[email protected]>
'1' 00-1F linux/timepps.h PPS kit from Ulrich Windl
<ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/>
'2' 01-04 linux/i2o.h
'3' 00-0F drivers/s390/char/raw3270.h conflict!
'3' 00-1F linux/suspend_ioctls.h, conflict!
kernel/power/user.c
'8' all SNP8023 advanced NIC card
<mailto:[email protected]>
';' 64-7F linux/vfio.h
';' 80-FF linux/iommufd.h
'=' 00-3f uapi/linux/ptp_clock.h <mailto:[email protected]>
'@' 00-0F linux/radeonfb.h conflict!
'@' 00-0F drivers/video/aty/aty128fb.c conflict!
'A' 00-1F linux/apm_bios.h conflict!
'A' 00-0F linux/agpgart.h, conflict!
drivers/char/agp/compat_ioctl.h
'A' 00-7F sound/asound.h conflict!
'B' 00-1F linux/cciss_ioctl.h conflict!
'B' 00-0F include/linux/pmu.h conflict!
'B' C0-FF advanced bbus <mailto:[email protected]>
'B' 00-0F xen/xenbus_dev.h conflict!
'C' all linux/soundcard.h conflict!
'C' 01-2F linux/capi.h conflict!
'C' F0-FF drivers/net/wan/cosa.h conflict!
'D' all arch/s390/include/asm/dasd.h
'D' 40-5F drivers/scsi/dpt/dtpi_ioctl.h Dead since 2022
'D' 05 drivers/scsi/pmcraid.h
'E' all linux/input.h conflict!
'E' 00-0F xen/evtchn.h conflict!
'F' all linux/fb.h conflict!
'F' 01-02 drivers/scsi/pmcraid.h conflict!
'F' 20 drivers/video/fsl-diu-fb.h conflict!
'F' 20 linux/ivtvfb.h conflict!
'F' 20 linux/matroxfb.h conflict!
'F' 20 drivers/video/aty/atyfb_base.c conflict!
'F' 00-0F video/da8xx-fb.h conflict!
'F' 80-8F linux/arcfb.h conflict!
'F' DD video/sstfb.h conflict!
'G' 00-3F drivers/misc/sgi-gru/grulib.h conflict!
'G' 00-0F xen/gntalloc.h, xen/gntdev.h conflict!
'H' 00-7F linux/hiddev.h conflict!
'H' 00-0F linux/hidraw.h conflict!
'H' 01 linux/mei.h conflict!
'H' 02 linux/mei.h conflict!
'H' 03 linux/mei.h conflict!
'H' 00-0F sound/asound.h conflict!
'H' 20-40 sound/asound_fm.h conflict!
'H' 80-8F sound/sfnt_info.h conflict!
'H' 10-8F sound/emu10k1.h conflict!
'H' 10-1F sound/sb16_csp.h conflict!
'H' 10-1F sound/hda_hwdep.h conflict!
'H' 40-4F sound/hdspm.h conflict!
'H' 40-4F sound/hdsp.h conflict!
'H' 90 sound/usb/usx2y/usb_stream.h
'H' 00-0F uapi/misc/habanalabs.h conflict!
'H' A0 uapi/linux/usb/cdc-wdm.h
'H' C0-F0 net/bluetooth/hci.h conflict!
'H' C0-DF net/bluetooth/hidp/hidp.h conflict!
'H' C0-DF net/bluetooth/cmtp/cmtp.h conflict!
'H' C0-DF net/bluetooth/bnep/bnep.h conflict!
'H' F1 linux/hid-roccat.h <mailto:[email protected]>
'H' F8-FA sound/firewire.h
'I' all linux/isdn.h conflict!
'I' 00-0F drivers/isdn/divert/isdn_divert.h conflict!
'I' 40-4F linux/mISDNif.h conflict!
'K' all linux/kd.h
'L' 00-1F linux/loop.h conflict!
'L' 10-1F drivers/scsi/mpt3sas/mpt3sas_ctl.h conflict!
'L' E0-FF linux/ppdd.h encrypted disk device driver
<http://linux01.gwdg.de/~alatham/ppdd.html>
'M' all linux/soundcard.h conflict!
'M' 01-16 mtd/mtd-abi.h conflict!
and drivers/mtd/mtdchar.c
'M' 01-03 drivers/scsi/megaraid/megaraid_sas.h
'M' 00-0F drivers/video/fsl-diu-fb.h conflict!
'N' 00-1F drivers/usb/scanner.h
'N' 40-7F drivers/block/nvme.c
'N' 80-8F uapi/linux/ntsync.h NT synchronization primitives
<mailto:[email protected]>
'O' 00-06 mtd/ubi-user.h UBI
'P' all linux/soundcard.h conflict!
'P' 60-6F sound/sscape_ioctl.h conflict!
'P' 00-0F drivers/usb/class/usblp.c conflict!
'P' 01-09 drivers/misc/pci_endpoint_test.c conflict!
'P' 00-0F xen/privcmd.h conflict!
'P' 00-05 linux/tps6594_pfsm.h conflict!
'Q' all linux/soundcard.h
'R' 00-1F linux/random.h conflict!
'R' 01 linux/rfkill.h conflict!
'R' 20-2F linux/trace_mmap.h
'R' C0-DF net/bluetooth/rfcomm.h
'R' E0 uapi/linux/fsl_mc.h
'S' all linux/cdrom.h conflict!
'S' 80-81 scsi/scsi_ioctl.h conflict!
'S' 82-FF scsi/scsi.h conflict!
'S' 00-7F sound/asequencer.h conflict!
'T' all linux/soundcard.h conflict!
'T' 00-AF sound/asound.h conflict!
'T' all arch/x86/include/asm/ioctls.h conflict!
'T' C0-DF linux/if_tun.h conflict!
'U' all sound/asound.h conflict!
'U' 00-CF linux/uinput.h conflict!
'U' 00-EF linux/usbdevice_fs.h
'U' C0-CF drivers/bluetooth/hci_uart.h
'V' all linux/vt.h conflict!
'V' all linux/videodev2.h conflict!
'V' C0 linux/ivtvfb.h conflict!
'V' C0 linux/ivtv.h conflict!
'V' C0 media/si4713.h conflict!
'W' 00-1F linux/watchdog.h conflict!
'W' 00-1F linux/wanrouter.h conflict! (pre 3.9)
'W' 00-3F sound/asound.h conflict!
'W' 40-5F drivers/pci/switch/switchtec.c
'W' 60-61 linux/watch_queue.h
'X' all fs/xfs/xfs_fs.h, conflict!
fs/xfs/linux-2.6/xfs_ioctl32.h,
include/linux/falloc.h,
linux/fs.h,
'X' all fs/ocfs2/ocfs_fs.h conflict!
'X' 01 linux/pktcdvd.h conflict!
'Z' 14-15 drivers/message/fusion/mptctl.h
'[' 00-3F linux/usb/tmc.h USB Test and Measurement Devices
<mailto:[email protected]>
'a' all linux/atm*.h, linux/sonet.h ATM on linux
<http://lrcwww.epfl.ch/>
'a' 00-0F drivers/crypto/qat/qat_common/adf_cfg_common.h conflict! qat driver
'b' 00-FF conflict! bit3 vme host bridge
<mailto:[email protected]>
'b' 00-0F linux/dma-buf.h conflict!
'c' 00-7F linux/comstats.h conflict!
'c' 00-7F linux/coda.h conflict!
'c' 00-1F linux/chio.h conflict!
'c' 80-9F arch/s390/include/asm/chsc.h conflict!
'c' A0-AF arch/x86/include/asm/msr.h conflict!
'd' 00-FF linux/char/drm/drm.h conflict!
'd' 02-40 pcmcia/ds.h conflict!
'd' F0-FF linux/digi1.h
'e' all linux/digi1.h conflict!
'f' 00-1F linux/ext2_fs.h conflict!
'f' 00-1F linux/ext3_fs.h conflict!
'f' 00-0F fs/jfs/jfs_dinode.h conflict!
'f' 00-0F fs/ext4/ext4.h conflict!
'f' 00-0F linux/fs.h conflict!
'f' 00-0F fs/ocfs2/ocfs2_fs.h conflict!
'f' 13-27 linux/fscrypt.h
'f' 81-8F linux/fsverity.h
'g' 00-0F linux/usb/gadgetfs.h
'g' 20-2F linux/usb/g_printer.h
'h' 00-7F conflict! Charon filesystem
<mailto:[email protected]>
'h' 00-1F linux/hpet.h conflict!
'h' 80-8F fs/hfsplus/ioctl.c
'i' 00-3F linux/i2o-dev.h conflict!
'i' 0B-1F linux/ipmi.h conflict!
'i' 80-8F linux/i8k.h
'i' 90-9F `linux/iio/*.h` IIO
'j' 00-3F linux/joystick.h
'k' 00-0F linux/spi/spidev.h conflict!
'k' 00-05 video/kyro.h conflict!
'k' 10-17 linux/hsi/hsi_char.h HSI character device
'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system
<http://web.archive.org/web/%2A/http://mikonos.dia.unisa.it/tcfs>
'l' 40-7F linux/udf_fs_i.h in development:
<https://github.com/pali/udftools>
'm' 00-09 linux/mmtimer.h conflict!
'm' all linux/mtio.h conflict!
'm' all linux/soundcard.h conflict!
'm' all linux/synclink.h conflict!
'm' 00-19 drivers/message/fusion/mptctl.h conflict!
'm' 00 drivers/scsi/megaraid/megaraid_ioctl.h conflict!
'n' 00-7F linux/ncp_fs.h and fs/ncpfs/ioctl.c
'n' 80-8F uapi/linux/nilfs2_api.h NILFS2
'n' E0-FF linux/matroxfb.h matroxfb
'o' 00-1F fs/ocfs2/ocfs2_fs.h OCFS2
'o' 00-03 mtd/ubi-user.h conflict! (OCFS2 and UBI overlaps)
'o' 40-41 mtd/ubi-user.h UBI
'o' 01-A1 `linux/dvb/*.h` DVB
'p' 00-0F linux/phantom.h conflict! (OpenHaptics needs this)
'p' 00-1F linux/rtc.h conflict!
'p' 40-7F linux/nvram.h
'p' 80-9F linux/ppdev.h user-space parport
<mailto:[email protected]>
'p' A1-A5 linux/pps.h LinuxPPS
<mailto:[email protected]>
'q' 00-1F linux/serio.h
'q' 80-FF linux/telephony.h Internet PhoneJACK, Internet LineJACK
linux/ixjuser.h <http://web.archive.org/web/%2A/http://www.quicknet.net>
'r' 00-1F linux/msdos_fs.h and fs/fat/dir.c
's' all linux/cdk.h
't' 00-7F linux/ppp-ioctl.h
't' 80-8F linux/isdn_ppp.h
't' 90-91 linux/toshiba.h toshiba and toshiba_acpi SMM
'u' 00-1F linux/smb_fs.h gone
'u' 00-2F linux/ublk_cmd.h conflict!
'u' 20-3F linux/uvcvideo.h USB video class host driver
'u' 40-4f linux/udmabuf.h userspace dma-buf misc device
'v' 00-1F linux/ext2_fs.h conflict!
'v' 00-1F linux/fs.h conflict!
'v' 00-0F linux/sonypi.h conflict!
'v' 00-0F media/v4l2-subdev.h conflict!
'v' 20-27 arch/powerpc/include/uapi/asm/vas-api.h VAS API
'v' C0-FF linux/meye.h conflict!
'w' all CERN SCI driver
'y' 00-1F packet based user level communications
<mailto:[email protected]>
'z' 00-3F CAN bus card conflict!
<mailto:[email protected]>
'z' 40-7F CAN bus card conflict!
<mailto:[email protected]>
'z' 10-4F drivers/s390/crypto/zcrypt_api.h conflict!
'|' 00-7F linux/media.h
0x80 00-1F linux/fb.h
0x81 00-1F linux/vduse.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
0x8A 00-1F linux/eventpoll.h
0x8B all linux/wireless.h
0x8C 00-3F WiNRADiO driver
<http://www.winradio.com.au/>
0x90 00 drivers/cdrom/sbpcd.h
0x92 00-0F drivers/usb/mon/mon_bin.c
0x93 60-7F linux/auto_fs.h
0x94 all fs/btrfs/ioctl.h Btrfs filesystem
and linux/fs.h some lifted to vfs/generic
0x97 00-7F fs/ceph/ioctl.h Ceph file system
0x99 00-0F 537-Addinboard driver
<mailto:[email protected]>
0xA0 all linux/sdp/sdp.h Industrial Device Project
<mailto:[email protected]>
0xA1 0 linux/vtpm_proxy.h TPM Emulator Proxy Driver
0xA2 all uapi/linux/acrn.h ACRN hypervisor
0xA3 80-8F Port ACL in development:
<mailto:[email protected]>
0xA3 90-9F linux/dtlk.h
0xA4 00-1F uapi/linux/tee.h Generic TEE subsystem
0xA4 00-1F uapi/asm/sgx.h <mailto:[email protected]>
0xA5 01-05 linux/surface_aggregator/cdev.h Microsoft Surface Platform System Aggregator
<mailto:[email protected]>
0xA5 20-2F linux/surface_aggregator/dtx.h Microsoft Surface DTX driver
<mailto:[email protected]>
0xAA 00-3F linux/uapi/linux/userfaultfd.h
0xAB 00-1F linux/nbd.h
0xAC 00-1F linux/raw.h
0xAD 00 Netfilter device in development:
<mailto:[email protected]>
0xAE 00-1F linux/kvm.h Kernel-based Virtual Machine
<mailto:[email protected]>
0xAE 40-FF linux/kvm.h Kernel-based Virtual Machine
<mailto:[email protected]>
0xAE 20-3F linux/nitro_enclaves.h Nitro Enclaves
0xAF 00-1F linux/fsl_hypervisor.h Freescale hypervisor
0xB0 all RATIO devices in development:
<mailto:[email protected]>
0xB1 00-1F PPPoX
<mailto:[email protected]>
0xB2 00 arch/powerpc/include/uapi/asm/papr-vpd.h powerpc/pseries VPD API
<mailto:linuxppc-dev>
0xB2 01-02 arch/powerpc/include/uapi/asm/papr-sysparm.h powerpc/pseries system parameter API
<mailto:linuxppc-dev>
0xB3 00 linux/mmc/ioctl.h
0xB4 00-0F linux/gpio.h <mailto:[email protected]>
0xB5 00-0F uapi/linux/rpmsg.h <mailto:[email protected]>
0xB6 all linux/fpga-dfl.h
0xB7 all uapi/linux/remoteproc_cdev.h <mailto:[email protected]>
0xB7 all uapi/linux/nsfs.h <mailto:Andrei Vagin <[email protected]>>
0xB8 01-02 uapi/misc/mrvl_cn10k_dpi.h Marvell CN10K DPI driver
0xC0 00-0F linux/usb/iowarrior.h
0xCA 00-0F uapi/misc/cxl.h
0xCA 10-2F uapi/misc/ocxl.h
0xCA 80-BF uapi/scsi/cxlflash_ioctl.h
0xCB 00-1F CBM serial IEC bus in development:
<mailto:[email protected]>
0xCC 00-0F drivers/misc/ibmvmc.h pseries VMC driver
0xCD 01 linux/reiserfs_fs.h
0xCE 01-02 uapi/linux/cxl_mem.h Compute Express Link Memory Devices
0xCF 02 fs/smb/client/cifs_ioctl.h
0xDB 00-0F drivers/char/mwave/mwavepub.h
0xDD 00-3F ZFCP device driver see drivers/s390/scsi/
<mailto:[email protected]>
0xE5 00-3F linux/fuse.h
0xEC 00-01 drivers/platform/chrome/cros_ec_dev.h ChromeOS EC driver
0xEE 00-09 uapi/linux/pfrut.h Platform Firmware Runtime Update and Telemetry
0xF3 00-3F drivers/usb/misc/sisusbvga/sisusb.h sisfb (in development)
<mailto:[email protected]>
0xF6 all LTTng Linux Trace Toolkit Next Generation
<mailto:[email protected]>
0xF8 all arch/x86/include/uapi/asm/amd_hsmp.h AMD HSMP EPYC system management interface driver
<mailto:[email protected]>
0xFD all linux/dm-ioctl.h
0xFE all linux/isst_if.h
==== ===== ======================================================= ================================================================
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