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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 all linux/umsdos_fs.h
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/>
81'6' 00-10 <asm-i386/processor.h> Intel IA32 microcode update driver
82 <mailto:tigran@veritas.com>
83'8' all SNP8023 advanced NIC card
84 <mailto:mcr@solidum.com>
85'A' 00-1F linux/apm_bios.h
86'B' C0-FF advanced bbus
87 <mailto:maassen@uni-freiburg.de>
88'C' all linux/soundcard.h
89'D' all asm-s390/dasd.h
90'F' all linux/fb.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' E0-FF linux/ppdd.h encrypted disk device driver
96 <http://linux01.gwdg.de/~alatham/ppdd.html>
97'M' all linux/soundcard.h conflict!
98'M' 00-1F linux/isicom.h conflict!
99'N' 00-1F drivers/usb/scanner.h
100'P' all linux/soundcard.h
101'Q' all linux/soundcard.h
102'R' 00-1F linux/random.h
103'S' all linux/cdrom.h conflict!
104'S' 80-81 scsi/scsi_ioctl.h conflict!
105'S' 82-FF scsi/scsi.h conflict!
106'T' all linux/soundcard.h conflict!
107'T' all asm-i386/ioctls.h conflict!
108'U' 00-EF linux/drivers/usb/usb.h
109'U' F0-FF drivers/usb/auerswald.c
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'a' all ATM on linux
116 <http://lrcwww.epfl.ch/linux-atm/magic.html>
117'b' 00-FF bit3 vme host bridge
118 <mailto:natalia@nikhefk.nikhef.nl>
119'c' 00-7F linux/comstats.h conflict!
120'c' 00-7F linux/coda.h conflict!
121'd' 00-FF linux/char/drm/drm/h conflict!
122'd' 00-1F linux/devfs_fs.h conflict!
123'd' 00-DF linux/video_decoder.h conflict!
124'd' F0-FF linux/digi1.h
125'e' all linux/digi1.h conflict!
126'e' 00-1F linux/video_encoder.h conflict!
127'e' 00-1F net/irda/irtty.h conflict!
128'f' 00-1F linux/ext2_fs.h
129'h' 00-7F Charon filesystem
130 <mailto:zapman@interlan.net>
131'i' 00-3F linux/i2o.h
132'j' 00-3F linux/joystick.h
133'k' all asm-sparc/kbio.h
134 asm-sparc64/kbio.h
135'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system
136 <http://mikonos.dia.unisa.it/tcfs>
137'l' 40-7F linux/udf_fs_i.h in development:
138 <http://www.trylinux.com/projects/udf/>
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' E0-FF video/matrox.h matroxfb
145'p' 00-3F linux/mc146818rtc.h
146'p' 40-7F linux/nvram.h
147'p' 80-9F user-space parport
148 <mailto:tim@cyberelk.net>
149'q' 00-1F linux/serio.h
150'q' 80-FF Internet PhoneJACK, Internet LineJACK
151 <http://www.quicknet.net>
152'r' 00-1F linux/msdos_fs.h
153's' all linux/cdk.h
154't' 00-7F linux/if_ppp.h
155't' 80-8F linux/isdn_ppp.h
156'u' 00-1F linux/smb_fs.h
157'v' 00-1F linux/ext2_fs.h conflict!
158'v' all linux/videodev.h conflict!
159'w' all CERN SCI driver
160'y' 00-1F packet based user level communications
161 <mailto:zapman@interlan.net>
162'z' 00-3F CAN bus card
163 <mailto:hdstich@connectu.ulm.circular.de>
164'z' 40-7F CAN bus card
165 <mailto:oe@port.de>
1660x80 00-1F linux/fb.h
1670x81 00-1F linux/videotext.h
1680x89 00-06 asm-i386/sockios.h
1690x89 0B-DF linux/sockios.h
1700x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range
1710x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range
1720x8B all linux/wireless.h
1730x8C 00-3F WiNRADiO driver
174 <http://www.proximity.com.au/~brian/winradio/>
1750x90 00 drivers/cdrom/sbpcd.h
1760x93 60-7F linux/auto_fs.h
1770x99 00-0F 537-Addinboard driver
178 <mailto:buk@buks.ipn.de>
1790xA0 all linux/sdp/sdp.h Industrial Device Project
180 <mailto:kenji@bitgate.com>
1810xA3 80-8F Port ACL in development:
182 <mailto:tlewis@mindspring.com>
1830xA3 90-9F linux/dtlk.h
1840xAB 00-1F linux/nbd.h
1850xAC 00-1F linux/raw.h
1860xAD 00 Netfilter device in development:
187 <mailto:rusty@rustcorp.com.au>
1880xB0 all RATIO devices in development:
189 <mailto:vgo@ratio.de>
1900xB1 00-1F PPPoX <mailto:mostrows@styx.uwaterloo.ca>
1910xCB 00-1F CBM serial IEC bus in development:
192 <mailto:michael.klein@puffin.lb.shuttle.de>
1930xDD 00-3F ZFCP device driver see drivers/s390/scsi/
194 <mailto:aherrman@de.ibm.com>
1950xF3 00-3F video/sisfb.h sisfb (in development)
196 <mailto:thomas@winischhofer.net>
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