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DESCRIPTION

#define FOOIOCTL fun(t,n,pt)

 

where the different variables and functions are:

FOOIOCTL

the name which will later be given in the ioctl(2) system call as second argument, e.g.,

ioctl(s, FOOIOCTL, ...)

.

fun()

a macro which can be one of

_IO

the call is a simple message to the kernel by itself. It does not copy anything into the kernel, nor does it want anything back.

_IOR

the call only reads parameters from the kernel and does not pass any to it

_IOW

the call only writes parameters to the kernel, but does not want anything back

_IOWR

the call writes data to the kernel and wants information back.

t

This integer describes to which subsystem the ioctl applies. t can be one of

'1'

pulse-per-second interface

'a'

ISO networking

'A'

ac devices (hp300)

'A'

Advanced Power Management (hpcmips, i386, sparc), see apm(4)

'A'

ADB devices (mac68k, macppc)

'A'

audio(4)

'b'

tb(4)

'b'

Bluetooth HCI sockets, see bluetooth(4)

'b'

Bluetooth Hub Control, see bthub(4)

'b'

Bluetooth SCO audio driver, see btsco(4)

'B'

bell device (x68k)

'B'

bpf(4)

'c'

coda

'c'

cd(4)

'c'

ch(4)

'C'

clock devices (amiga, atari, hp300, x68k)

'd'

the disk subsystem

'E'

envsys(4)

'f'

files

'F'

Sun-compatible framebuffers

'F'

ccd(4) and vnd(4)

'g'

qdss framebuffers

'G'

grf devices (amiga, atari, hp300, mac68k, x68k)

'h'

HIL devices (hp300)

'H'

HIL devices (hp300)

'H'

HPc framebuffers

'i'

a (pseudo) interface

'I'

ite(4) (mac68k)

'J'

ISA joystick interface

'k'

Sun-compatible (and other) keyboards

'l'

leo devices (atari)

'm'

mtio(4)

'M'

mouse devices (atari)

'M'

mlx(4)

'n'

virtual console device (arm32)

'n'

SMB networking

'O'

OpenPROM and OpenFirmware

'p'

power control (x68k)

'P'

parallel port (amiga, x68k)

'P'

profiling (arm32)

'P'

printer/plotter interface (hp300)

'P'

pci(4)

'P'

compat/ossaudio and soundcard.h

'P'

magma(4) bpp (sparc)

'q'

altq(9)

'q'

pmax graphics devices

'Q'

altq(9)

'Q'

raw SCSI commands

'r'

the routing subsystem

'r'

md(4)

'R'

rnd(4)

's'

the socket layer

'S'

SCSI disks (arc, hp300, pmax)

'S'

watchdog devices (sh3)

'S'

ISA speaker devices

'S'

stic devices

'S'

scanners

't'

the tty layer

'u'

user defined ???

'U'

scsibus (see scsi(4))

'v'

Sun-compatible “firm events”

'V'

view device (amiga, atari)

'V'

sram device (x68k)

'w'

watchdog devices

'W'

wt devices

'W'

wscons devices

'x'

bt8xx devices

'Z'

ite devices (amiga, atari, x68k)

'Z'

passthrough ioctls

n

This numbers the ioctl within the group. There may be only one n for a given t. This is an unsigned 8 bit number.

pt

This specifies the type of the passed parameter. This one gets internally transformed to the size of the parameter, so for example, if you want to pass a structure, then you have to specify that structure and not a pointer to it or sizeof(struct foo)

In order for the new ioctl to be known to the system it is installed in either ⟨sys/ioctl.h⟩ or one of the files that are reached from ⟨sys/ioctl.h⟩.

#define	FOOIOCTL	_IOWR('i', 23, int)

int a = 3;
error = ioctl(s, FOOICTL, &a);

driver_ioctl(..., u_long cmd, void *data)
{
	...
	switch (cmd) {

	case FOOIOCTL:
		int *a = (int *)data;
		printf(" Value passed: %d\n", *a);
		break;
	}
}