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1 Ioctl Numbers
2 19 October 1999
3 Michael Elizabeth Chastain
4 <mec@shout.net>
6 If you are adding new ioctl's to the kernel, you should use the _IO
7 macros 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
15 system calls 'write' and 'read'. For example, a SET_FOO ioctl would
16 be _IOW, although the kernel would actually read data from user space;
17 a GET_FOO ioctl would be _IOR, although the kernel would actually write
18 data to user space.
20 The first argument to _IO, _IOW, _IOR, or _IOWR is an identifying letter
21 or number from the table below. Because of the large number of drivers,
22 many drivers share a partial letter with other drivers.
24 If you are writing a driver for a new device and need a letter, pick an
25 unused block with enough room for expansion: 32 to 256 ioctl commands.
26 You can register the block by patching this file and submitting the
27 patch to Linus Torvalds. Or you can e-mail me at <mec@shout.net> and
28 I'll register one for you.
30 The second argument to _IO, _IOW, _IOR, or _IOWR is a sequence number
31 to 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
33 out of the kernel (e.g. 'int' or 'struct foo'). NOTE! Do NOT use
34 sizeof(arg) as the third argument as this results in your ioctl thinking
35 it passes an argument of type size_t.
37 Some devices use their major number as the identifier; this is OK, as
38 long as it is unique. Some devices are irregular and don't follow any
39 convention at all.
41 Following 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.
59 This table lists ioctls visible from user land for Linux/i386. It contains
60 most drivers up to 2.3.14, but I know I am missing some.
62 Code Seq# Include File Comments
63 ========================================================
64 0x00 00-1F linux/fs.h conflict!
65 0x00 00-1F scsi/scsi_ioctl.h conflict!
66 0x00 00-1F linux/fb.h conflict!
67 0x00 00-1F linux/wavefront.h conflict!
68 0x02 all linux/fd.h
69 0x03 all linux/hdreg.h
70 0x04 D2-DC linux/umsdos_fs.h Dead since 2.6.11, but don't reuse these.
71 0x06 all linux/lp.h
72 0x09 all linux/md.h
73 0x12 all linux/fs.h
74 linux/blkpg.h
75 0x1b all InfiniBand Subsystem <http://www.openib.org/>
76 0x20 all drivers/cdrom/cm206.h
77 0x22 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 'd' 00-FF linux/char/drm/drm/h conflict!
125 'd' 00-DF linux/video_decoder.h conflict!
126 'd' F0-FF linux/digi1.h
127 'e' all linux/digi1.h conflict!
128 'e' 00-1F linux/video_encoder.h conflict!
129 'e' 00-1F net/irda/irtty.h conflict!
130 'f' 00-1F linux/ext2_fs.h
131 'h' 00-7F Charon filesystem
132 <mailto:zapman@interlan.net>
133 'i' 00-3F linux/i2o.h
134 'j' 00-3F linux/joystick.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://sourceforge.net/projects/linux-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 'o' 00-1F fs/ocfs2/ocfs2_fs.h OCFS2
146 'o' 00-03 include/mtd/ubi-user.h conflict! (OCFS2 and UBI overlaps)
147 'o' 40-41 include/mtd/ubi-user.h UBI
148 'o' 01-A1 include/linux/dvb/*.h DVB
149 'p' 00-0F linux/phantom.h conflict! (OpenHaptics needs this)
150 'p' 00-3F linux/mc146818rtc.h conflict!
151 'p' 40-7F linux/nvram.h
152 'p' 80-9F user-space parport
153 <mailto:tim@cyberelk.net>
154 'q' 00-1F linux/serio.h
155 'q' 80-FF Internet PhoneJACK, Internet LineJACK
156 <http://www.quicknet.net>
157 'r' 00-1F linux/msdos_fs.h
158 's' all linux/cdk.h
159 't' 00-7F linux/if_ppp.h
160 't' 80-8F linux/isdn_ppp.h
161 'u' 00-1F linux/smb_fs.h
162 'v' 00-1F linux/ext2_fs.h conflict!
163 'v' all linux/videodev.h conflict!
164 'w' all CERN SCI driver
165 'y' 00-1F packet based user level communications
166 <mailto:zapman@interlan.net>
167 'z' 00-3F CAN bus card
168 <mailto:hdstich@connectu.ulm.circular.de>
169 'z' 40-7F CAN bus card
170 <mailto:oe@port.de>
171 0x80 00-1F linux/fb.h
172 0x81 00-1F linux/videotext.h
173 0x89 00-06 arch/x86/include/asm/sockios.h
174 0x89 0B-DF linux/sockios.h
175 0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range
176 0x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range
177 0x8B all linux/wireless.h
178 0x8C 00-3F WiNRADiO driver
179 <http://www.proximity.com.au/~brian/winradio/>
180 0x90 00 drivers/cdrom/sbpcd.h
181 0x93 60-7F linux/auto_fs.h
182 0x99 00-0F 537-Addinboard driver
183 <mailto:buk@buks.ipn.de>
184 0xA0 all linux/sdp/sdp.h Industrial Device Project
185 <mailto:kenji@bitgate.com>
186 0xA3 80-8F Port ACL in development:
187 <mailto:tlewis@mindspring.com>
188 0xA3 90-9F linux/dtlk.h
189 0xAB 00-1F linux/nbd.h
190 0xAC 00-1F linux/raw.h
191 0xAD 00 Netfilter device in development:
192 <mailto:rusty@rustcorp.com.au>
193 0xAE all linux/kvm.h Kernel-based Virtual Machine
194 <mailto:kvm-devel@lists.sourceforge.net>
195 0xB0 all RATIO devices in development:
196 <mailto:vgo@ratio.de>
197 0xB1 00-1F PPPoX <mailto:mostrows@styx.uwaterloo.ca>
198 0xCB 00-1F CBM serial IEC bus in development:
199 <mailto:michael.klein@puffin.lb.shuttle.de>
200 0xDD 00-3F ZFCP device driver see drivers/s390/scsi/
201 <mailto:aherrman@de.ibm.com>
202 0xF3 00-3F video/sisfb.h sisfb (in development)
203 <mailto:thomas@winischhofer.net>
204 0xF4 00-1F video/mbxfb.h mbxfb
205 <mailto:raph@8d.com>