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 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
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
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!
69 0x03 all linux/hdreg.h
70 0x04 D2-DC linux/umsdos_fs.h Dead since 2.6.11, but don't reuse these.
75 0x1b all InfiniBand Subsystem <http://www.openib.org/>
76 0x20 all drivers/cdrom/cm206.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 asm-s390/dasd.h
90 'H' all linux/hiddev.h
92 'J' 00-1F drivers/scsi/gdth_ioctl.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
98 'N' 00-1F drivers/usb/scanner.h
99 'P' all linux/soundcard.h
100 'Q' all linux/soundcard.h
101 'R' 00-1F linux/random.h
102 'S' all linux/cdrom.h conflict!
103 'S' 80-81 scsi/scsi_ioctl.h conflict!
104 'S' 82-FF scsi/scsi.h conflict!
105 'T' all linux/soundcard.h conflict!
106 'T' all asm-i386/ioctls.h conflict!
107 'U' 00-EF linux/drivers/usb/usb.h
109 'W' 00-1F linux/watchdog.h conflict!
110 'W' 00-1F linux/wanrouter.h conflict!
111 'X' all linux/xfs_fs.h
112 'Y' all linux/cyclades.h
114 <http://lrcwww.epfl.ch/linux-atm/magic.html>
115 'b' 00-FF bit3 vme host bridge
116 <mailto:natalia@nikhefk.nikhef.nl>
117 'c' 00-7F linux/comstats.h conflict!
118 'c' 00-7F linux/coda.h conflict!
119 'c' 80-9F asm-s390/chsc.h
120 'd' 00-FF linux/char/drm/drm/h conflict!
121 'd' 00-DF linux/video_decoder.h conflict!
122 'd' F0-FF linux/digi1.h
123 'e' all linux/digi1.h conflict!
124 'e' 00-1F linux/video_encoder.h conflict!
125 'e' 00-1F net/irda/irtty.h conflict!
126 'f' 00-1F linux/ext2_fs.h
127 'h' 00-7F Charon filesystem
128 <mailto:zapman@interlan.net>
129 'i' 00-3F linux/i2o.h
130 'j' 00-3F linux/joystick.h
131 'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system
132 <http://mikonos.dia.unisa.it/tcfs>
133 'l' 40-7F linux/udf_fs_i.h in development:
134 <http://sourceforge.net/projects/linux-udf/>
135 'm' all linux/mtio.h conflict!
136 'm' all linux/soundcard.h conflict!
137 'm' all linux/synclink.h conflict!
138 'm' 00-1F net/irda/irmod.h conflict!
139 'n' 00-7F linux/ncp_fs.h
140 'n' E0-FF video/matrox.h matroxfb
141 'o' 00-1F fs/ocfs2/ocfs2_fs.h OCFS2
142 'p' 00-0F linux/phantom.h conflict! (OpenHaptics needs this)
143 'p' 00-3F linux/mc146818rtc.h conflict!
144 'p' 40-7F linux/nvram.h
145 'p' 80-9F user-space parport
146 <mailto:tim@cyberelk.net>
147 'q' 00-1F linux/serio.h
148 'q' 80-FF Internet PhoneJACK, Internet LineJACK
149 <http://www.quicknet.net>
150 'r' 00-1F linux/msdos_fs.h
152 't' 00-7F linux/if_ppp.h
153 't' 80-8F linux/isdn_ppp.h
154 'u' 00-1F linux/smb_fs.h
155 'v' 00-1F linux/ext2_fs.h conflict!
156 'v' all linux/videodev.h conflict!
157 'w' all CERN SCI driver
158 'y' 00-1F packet based user level communications
159 <mailto:zapman@interlan.net>
160 'z' 00-3F CAN bus card
161 <mailto:hdstich@connectu.ulm.circular.de>
162 'z' 40-7F CAN bus card
164 0x80 00-1F linux/fb.h
165 0x81 00-1F linux/videotext.h
166 0x89 00-06 asm-i386/sockios.h
167 0x89 0B-DF linux/sockios.h
168 0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range
169 0x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range
170 0x8B all linux/wireless.h
171 0x8C 00-3F WiNRADiO driver
172 <http://www.proximity.com.au/~brian/winradio/>
173 0x90 00 drivers/cdrom/sbpcd.h
174 0x93 60-7F linux/auto_fs.h
175 0x99 00-0F 537-Addinboard driver
176 <mailto:buk@buks.ipn.de>
177 0xA0 all linux/sdp/sdp.h Industrial Device Project
178 <mailto:kenji@bitgate.com>
179 0xA3 80-8F Port ACL in development:
180 <mailto:tlewis@mindspring.com>
181 0xA3 90-9F linux/dtlk.h
182 0xAB 00-1F linux/nbd.h
183 0xAC 00-1F linux/raw.h
184 0xAD 00 Netfilter device in development:
185 <mailto:rusty@rustcorp.com.au>
186 0xAE all linux/kvm.h Kernel-based Virtual Machine
187 <mailto:kvm-devel@lists.sourceforge.net>
188 0xB0 all RATIO devices in development:
189 <mailto:vgo@ratio.de>
190 0xB1 00-1F PPPoX <mailto:mostrows@styx.uwaterloo.ca>
191 0xCB 00-1F CBM serial IEC bus in development:
192 <mailto:michael.klein@puffin.lb.shuttle.de>
193 0xDD 00-3F ZFCP device driver see drivers/s390/scsi/
194 <mailto:aherrman@de.ibm.com>
195 0xF3 00-3F video/sisfb.h sisfb (in development)
196 <mailto:thomas@winischhofer.net>
197 0xF4 00-1F video/mbxfb.h mbxfb
projects / linux-2.6 / blob