kernel26-2.6.12-alx-r9/Documentation/ioctl-number.txt

Ioctl Numbers
19 October 1999
Michael Elizabeth Chastain
<mec@shout.net>

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 <mec@shout.net> 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/i386.  It contains
most drivers up to 2.3.14, but I know I am missing some.

Code	Seq#	Include File		Comments
========================================================
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	all	linux/umsdos_fs.h
0x06	all	linux/lp.h
0x09	all	linux/md.h
0x12	all	linux/fs.h
		linux/blkpg.h
0x1b	all	InfiniBand Subsystem	<http://www.openib.org/>
0x20	all	drivers/cdrom/cm206.h
0x22	all	scsi/sg.h
'#'	00-3F	IEEE 1394 Subsystem	Block for the entire subsystem
'1'	00-1F	<linux/timepps.h>	PPS kit from Ulrich Windl
					<ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/>
'6'	00-10	<asm-i386/processor.h>	Intel IA32 microcode update driver
					<mailto:tigran@veritas.com>
'8'	all				SNP8023 advanced NIC card
					<mailto:mcr@solidum.com>
'A'	00-1F	linux/apm_bios.h
'B'	C0-FF				advanced bbus
					<mailto:maassen@uni-freiburg.de>
'C'	all	linux/soundcard.h
'D'	all	asm-s390/dasd.h
'F'	all	linux/fb.h
'I'	all	linux/isdn.h
'J'	00-1F	drivers/scsi/gdth_ioctl.h
'K'	all	linux/kd.h
'L'	00-1F	linux/loop.h
'L'	E0-FF	linux/ppdd.h		encrypted disk device driver
					<http://linux01.gwdg.de/~alatham/ppdd.html>
'M'	all	linux/soundcard.h	conflict!
'M'	00-1F	linux/isicom.h		conflict!
'N'	00-1F	drivers/usb/scanner.h
'P'	all	linux/soundcard.h
'Q'	all	linux/soundcard.h
'R'	00-1F	linux/random.h
'S'	all	linux/cdrom.h		conflict!
'S'	80-81	scsi/scsi_ioctl.h	conflict!
'S'	82-FF	scsi/scsi.h		conflict!
'T'	all	linux/soundcard.h	conflict!
'T'	all	asm-i386/ioctls.h	conflict!
'U'	00-EF	linux/drivers/usb/usb.h
'U'	F0-FF	drivers/usb/auerswald.c
'V'	all	linux/vt.h
'W'	00-1F	linux/watchdog.h	conflict!
'W'	00-1F	linux/wanrouter.h	conflict!
'X'	all	linux/xfs_fs.h
'Y'	all	linux/cyclades.h
'a'	all				ATM on linux
					<http://lrcwww.epfl.ch/linux-atm/magic.html>
'b'	00-FF				bit3 vme host bridge
					<mailto:natalia@nikhefk.nikhef.nl>
'c'	00-7F	linux/comstats.h	conflict!
'c'	00-7F	linux/coda.h		conflict!
'd'	00-FF	linux/char/drm/drm/h	conflict!
'd'	00-1F	linux/devfs_fs.h	conflict!
'd'	00-DF	linux/video_decoder.h	conflict!
'd'	F0-FF	linux/digi1.h
'e'	all	linux/digi1.h		conflict!
'e'	00-1F	linux/video_encoder.h	conflict!
'e'	00-1F	net/irda/irtty.h	conflict!
'f'	00-1F	linux/ext2_fs.h
'h'	00-7F				Charon filesystem
					<mailto:zapman@interlan.net>
'i'	00-3F	linux/i2o.h
'j'	00-3F	linux/joystick.h
'k'	all	asm-sparc/kbio.h
		asm-sparc64/kbio.h
'l'	00-3F	linux/tcfs_fs.h		transparent cryptographic file system
					<http://mikonos.dia.unisa.it/tcfs>
'l'	40-7F	linux/udf_fs_i.h	in development:
					<http://www.trylinux.com/projects/udf/>
'm'	all	linux/mtio.h		conflict!
'm'	all	linux/soundcard.h	conflict!
'm'	all	linux/synclink.h	conflict!
'm'	00-1F	net/irda/irmod.h	conflict!
'n'	00-7F	linux/ncp_fs.h
'n'	E0-FF	video/matrox.h          matroxfb
'p'	00-3F	linux/mc146818rtc.h
'p'	40-7F	linux/nvram.h
'p'	80-9F				user-space parport
					<mailto:tim@cyberelk.net>
'q'	00-1F	linux/serio.h
'q'	80-FF				Internet PhoneJACK, Internet LineJACK
					<http://www.quicknet.net>
'r'	00-1F	linux/msdos_fs.h
's'	all	linux/cdk.h
't'	00-7F	linux/if_ppp.h
't'	80-8F	linux/isdn_ppp.h
'u'	00-1F	linux/smb_fs.h
'v'	00-1F	linux/ext2_fs.h		conflict!
'v'	all	linux/videodev.h	conflict!
'w'	all				CERN SCI driver
'y'	00-1F				packet based user level communications
					<mailto:zapman@interlan.net>
'z'	00-3F				CAN bus card
					<mailto:hdstich@connectu.ulm.circular.de>
'z'	40-7F				CAN bus card
					<mailto:oe@port.de>
0x80	00-1F	linux/fb.h
0x81	00-1F	linux/videotext.h
0x89	00-06	asm-i386/sockios.h
0x89	0B-DF	linux/sockios.h
0x89	E0-EF	linux/sockios.h		SIOCPROTOPRIVATE range
0x89	F0-FF	linux/sockios.h		SIOCDEVPRIVATE range
0x8B	all	linux/wireless.h
0x8C	00-3F				WiNRADiO driver
					<http://www.proximity.com.au/~brian/winradio/>
0x90	00	drivers/cdrom/sbpcd.h
0x93	60-7F	linux/auto_fs.h
0x99	00-0F				537-Addinboard driver
					<mailto:buk@buks.ipn.de>
0xA0	all	linux/sdp/sdp.h		Industrial Device Project
					<mailto:kenji@bitgate.com>
0xA3	80-8F	Port ACL		in development:
					<mailto:tlewis@mindspring.com>
0xA3	90-9F	linux/dtlk.h
0xAB	00-1F	linux/nbd.h
0xAC	00-1F	linux/raw.h
0xAD	00	Netfilter device	in development:
					<mailto:rusty@rustcorp.com.au>	
0xB0	all	RATIO devices		in development:
					<mailto:vgo@ratio.de>
0xB1	00-1F	PPPoX			<mailto:mostrows@styx.uwaterloo.ca>
0xCB	00-1F	CBM serial IEC bus	in development:
					<mailto:michael.klein@puffin.lb.shuttle.de>
0xDD	00-3F	ZFCP device driver	see drivers/s390/scsi/
					<mailto:aherrman@de.ibm.com>
0xF3	00-3F	video/sisfb.h		sisfb (in development)
					<mailto:thomas@winischhofer.net>
1	Ioctl Numbers
2	19 October 1999
3	Michael Elizabeth Chastain
4	<mec@shout.net>
5
6	If you are adding new ioctl's to the kernel, you should use the _IO
7	macros 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
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.
19
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.
23
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.
29
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.
36
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.
40
41	Following 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
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.
61
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 all linux/umsdos_fs.h
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	'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>
166	0x80 00-1F linux/fb.h
167	0x81 00-1F linux/videotext.h
168	0x89 00-06 asm-i386/sockios.h
169	0x89 0B-DF linux/sockios.h
170	0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range
171	0x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range
172	0x8B all linux/wireless.h
173	0x8C 00-3F WiNRADiO driver
174	<http://www.proximity.com.au/~brian/winradio/>
175	0x90 00 drivers/cdrom/sbpcd.h
176	0x93 60-7F linux/auto_fs.h
177	0x99 00-0F 537-Addinboard driver
178	<mailto:buk@buks.ipn.de>
179	0xA0 all linux/sdp/sdp.h Industrial Device Project
180	<mailto:kenji@bitgate.com>
181	0xA3 80-8F Port ACL in development:
182	<mailto:tlewis@mindspring.com>
183	0xA3 90-9F linux/dtlk.h
184	0xAB 00-1F linux/nbd.h
185	0xAC 00-1F linux/raw.h
186	0xAD 00 Netfilter device in development:
187	<mailto:rusty@rustcorp.com.au>
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>