3 Michael Elizabeth Chastain
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
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 is the size
32 of the structure going into the kernel or coming out of the kernel.
34 Some devices use their major number as the identifier; this is OK, as
35 long as it is unique. Some devices are irregular and don't follow any
38 Following this convention is good because:
40 (1) Keeping the ioctl's globally unique helps error checking:
41 if a program calls an ioctl on the wrong device, it will get an
42 error rather than some unexpected behaviour.
44 (2) The 'strace' build procedure automatically finds ioctl numbers
45 defined with _IO, _IOW, _IOR, or _IOWR.
47 (3) 'strace' can decode numbers back into useful names when the
50 (4) People looking for ioctls can grep for them more easily when
51 this convention is used to define the ioctl numbers.
53 (5) When following the convention, the driver code can use generic
54 code to copy the parameters between user and kernel space.
56 This table lists ioctls visible from user land for Linux/i386. It contains
57 most drivers up to 2.3.14, but I know I am missing some.
59 Code Seq# Include File Comments
60 ========================================================
61 0x00 00-1F linux/fs.h conflict!
62 0x00 00-1F scsi/scsi_ioctl.h conflict!
63 0x00 00-1F linux/fb.h conflict!
64 0x00 00-1F linux/wavefront.h conflict!
66 0x03 all linux/hdreg.h
67 0x04 all linux/umsdos_fs.h
72 0x20 all drivers/cdrom/cm206.h
74 '1' 00-1F <linux/timepps.h> PPS kit from Ulrich Windl
75 <ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/>
76 '8' all SNP8023 advanced NIC card
77 <mailto:mcr@solidum.com>
78 'A' 00-1F linux/apm_bios.h
79 'B' C0-FF advanced bbus
80 <mailto:maassen@uni-freiburg.de>
81 'C' all linux/soundcard.h
84 'J' 00-1F drivers/scsi/gdth_ioctl.h
86 'L' 00-1F linux/loop.h
87 'L' E0-FF linux/ppdd.h encrypted disk device driver
88 <http://linux01.gwdg.de/~alatham/ppdd.html>
89 'M' all linux/soundcard.h conflict!
90 'M' 00-1F linux/isicom.h conflict!
91 'P' all linux/soundcard.h
92 'Q' all linux/soundcard.h
93 'R' 00-1F linux/random.h
94 'S' all linux/cdrom.h conflict!
95 'S' 80-81 scsi/scsi_ioctl.h conflict!
96 'S' 82-FF scsi/scsi.h conflict!
97 'T' all linux/soundcard.h conflict!
98 'T' all asm-i386/ioctls.h conflict!
99 'U' all linux/drivers/usb/usb.h
101 'W' 00-1F linux/watchdog.h conflict!
102 'W' 00-1F linux/wanrouter.h conflict!
103 'Y' all linux/cyclades.h
105 <http://lrcwww.epfl.ch/linux-atm/magic.html>
106 'b' 00-FF bit3 vme host bridge
107 <mailto:natalia@nikhefk.nikhef.nl>
108 'c' 00-7F linux/comstats.h conflict!
109 'c' 00-7F linux/coda.h conflict!
110 'd' 00-1F linux/devfs_fs.h conflict!
111 'd' 00-DF linux/video_decoder.h conflict!
112 'd' F0-FF linux/digi1.h
113 'e' all linux/digi1.h conflict!
114 'e' 00-1F linux/video_encoder.h conflict!
115 'e' 00-1F net/irda/irtty.h conflict!
116 'f' 00-1F linux/ext2_fs.h
117 'i' 00-3F linux/i2o.h
118 'j' 00-3F linux/joystick.h
119 'k' all asm-sparc/kbio.h
121 'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system
122 <http://mikonos.dia.unisa.it/tcfs>
123 'm' all linux/mtio.h conflict!
124 'm' all linux/soundcard.h conflict!
125 'm' all linux/synclink.h conflict!
126 'm' 00-1F net/irda/irmod.h conflict!
127 'n' all linux/ncp_fs.h
128 'p' 00-3F linux/mc146818rtc.h
129 'p' 40-7F linux/nvram.h
130 'p' 80-9F user-space parport
131 <mailto:tim@cyberelk.demon.co.uk>
132 'q' 00-1F linux/videotext.h conflict!
133 'q' 80-FF Internet PhoneJACK, Internet LineJACK
134 <http://www.quicknet.net>
135 'r' 00-1F linux/msdos_fs.h
137 't' 00-7F linux/if_ppp.h
138 't' 80-8F linux/isdn_ppp.h
139 'u' 00-1F linux/smb_fs.h
140 'v' 00-1F linux/ext2_fs.h conflict!
141 'v' all linux/videodev.h conflict!
142 'w' all CERN SCI driver
143 'z' 00-3F CAN bus card
144 <mailto:hdstich@connectu.ulm.circular.de>
145 'z' 40-7F CAN bus card
147 0x80 00-1F linux/fb.h
148 0x89 00-06 asm-i386/sockios.h
149 0x89 0B-DF linux/sockios.h
150 0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range
151 0x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range
152 0x8B all linux/wireless.h
153 0x8C 00-3F WiNRADiO driver
154 <http://www.proximity.com.au/~brian/winradio/>
155 0x90 00 drivers/cdrom/sbpcd.h
156 0x93 60-7F linux/auto_fs.h
157 0x99 00-0F 537-Addinboard driver
158 <mailto:buk@buks.ipn.de>
159 0xA0 all linux/sdp/sdp.h Industrial Device Project
160 <mailto:kenji@bitgate.com>
161 0xA3 00-1F Philips SAA7146 dirver in development:
162 <mailto:Andreas.Beckmann@hamburg.sc.philips.com>
163 0xA3 80-8F Port ACL in development:
164 <mailto:tlewis@mindspring.com>
165 0xA3 90-9F linux/dtlk.h
166 0xAB 00-1F linux/nbd.h
167 0xAC 00-1F linux/raw.h
168 0xAD 00 Netfilter device in development:
169 <mailto:rusty@rustcorp.com.au>
170 0xB0 all RATIO devices in development:
171 <mailto:vgo@ratio.de>